JP2007080998A - Image display device, planar light source device and liquid crystal display device assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device which has an incorporated GaN-based semiconductor light-emitting element and enables to further widen a color reproduction range without causing an increase in a manufacturing cost such as an increase in the number of components. <P>SOLUTION: The image display device consists of a first image display device 50B provided with a first light-emitting element 1B for emitting blue light, a second image display device 50G provided with a second light-emitting element 1G for emitting green light, and a third image display device 50R provided with a third light-emitting element 1R for emitting red light. In this device, an image is formed of the blue, green and red lights emitted from the first, second and third image display devices 50B, 50G and 50R, at least any one of the first, second and third light-emitting elements 1B, 1G and 1R is configured by a GaN-based semiconductor light-emitting element, and the GaN-based semiconductor light-emitting element emits a light of a different wavelength based on different operation current density. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device, a planar light source device, and a liquid crystal display device assembly in which a GaN-based semiconductor light emitting element is incorporated.

  Usually, an image display device that displays a color image has three primary colors of red / green / blue, and a phosphor in a cathode ray tube, a color filter in a liquid crystal display device, and the like are selected so as to obtain desired three primary colors. Yes. Such a color gamut expressed by the three primary colors of red / green / blue is represented by a triangle with the chromaticity points of the three primary colors as vertices on the chromaticity diagram, and is typically the NTSC standard or the EBU standard. There are various standards such as the Adobe RGB standard and the sRGB standard. Conventional cathode ray tubes were based on the EBU standard and the sRGB standard, but in recent years in liquid crystal display devices using three colors (three types) of light emitting diodes of red / green / blue as a planar light source device (backlight). A wide color gamut apparatus that covers the NTSC standard and the Adobe RGB standard is also commercially available.

  Further, in order to express various colors existing in the natural world, an image display apparatus using more primary colors has been proposed. For example, an image display device that can express a wide color gamut of 181% with respect to the sRGB standard by using six types of light emitting diodes that emit six colors of 410 nm, 510 nm, 540 nm, 615 nm, and 625 nm has been proposed. (See Nikkei Electronics article http://techon.nikkeibp.co.jp/article/NEWS/20050510/104520/). Furthermore, not only a liquid crystal display device but also an image display device using a light emitting diode as a light source is applied to, for example, an outdoor large direct-view image display device, and further, a small direct-view type or projection type image display device. Etc. have been proposed at the development level.

  In a light-emitting device (GaN-based semiconductor light-emitting device) having an active layer made of a gallium nitride (GaN) -based compound semiconductor, the band gap energy is controlled by the mixed crystal composition and thickness of the active layer, so that ultraviolet to infrared is controlled. Emission wavelengths over a wide range up to can be realized. GaN-based semiconductor light-emitting elements that emit various colors are already on the market and are used in a wide range of applications such as image display devices, illumination devices, inspection devices, and disinfection light sources. In addition, semiconductor lasers and light emitting diodes (LEDs) that emit blue-violet light have been developed, and are used as pickups for writing and reading large capacity optical disks.

  In general, it is known that the GaN-based semiconductor light-emitting element shifts the emission wavelength to the short wavelength side when the drive current (operating current) increases. For example, when the drive current is increased from 20 mA to 100 mA, A shift in emission wavelength of −3 nm in the blue light emitting region and −19 nm in the green light emitting region has been reported (for example, Nichia Chemical Co., Ltd. product specification NSPB500S and Nichia Chemical Co., Ltd. product specification). NSPG500S).

  A phenomenon such as a shift in emission wavelength due to an increase in driving current (operating current) is particularly common in an active layer made of a GaN-based compound semiconductor containing In atoms having an emission wavelength longer than visible light. It is a problem, the localization of carriers by In atoms in the well layer constituting the active layer (for example, see Y. Kawakami, et al., J. Phys. Condens. Matter 13 (2001) pp. 6993), It is thought that the internal electric field effect due to lattice mismatch (see SF Chichibu, Materials Science and Engineering B59 (1999) pp.298) is involved.

  By the way, for example, in Japanese Patent Laid-Open No. 2002-237619, a light emitting diode that emits a plurality of colors by supplying a pulse current having a plurality of peak current values to a light emitting diode whose emission wavelength changes by changing a current value. A method for controlling the emission color of a diode is disclosed. As a result, in the light emission color control method of the light emitting diode, it is possible to reduce the size of the light emission source as one place and to easily control the light emission color.

  In the GaN-based semiconductor light-emitting device, various techniques have been proposed for an active layer having a multiple quantum well structure including a well layer and a barrier layer, for example, for high efficiency. For example, JP 2003-520453 A is disclosed. Discloses a semiconductor light emitting device in which a light emitting active layer or a barrier layer is chirped in an active layer having a multiple quantum well structure having at least two light emitting active layers and at least one barrier layer. Here, chirping means forming these layers so that the thickness and / or composition of a plurality of similar layers are not uniform or asymmetric. And by setting it as such a structure, the light output or light generation efficiency of each well layer in LED which has a multiple quantum well structure is raised.

  More specifically, in the paragraph number [0031] of this patent application publication, only the thicknesses of the active layers 48 to 56 in the LED 30 are chirped as a first example, and the active layer in the active region 36 is 48, 50, 52, 54 and 56 are disclosed configured to have thicknesses of 200, 300, 400, 500 and 600 angstroms, respectively. Moreover, in the paragraph number [0032] of this patent application publication publication, as a third example, only the thickness of the barrier layers 58 to 64 is chirped, and the barrier layer is approximately 10 angstroms to approximately 500 angstroms or more. And the barrier layer positioned closer to the n-type lower sealing layer 34 is thicker than the barrier layer positioned away from the n-type lower sealing layer 34. Is disclosed.

JP 2002-237619 A Special table 2003-520453 http://techon.nikkeibp.co.jp/article/NEWS/20050510/104520/ Nichia Corporation Product Specification NSPB500S Nichia Corporation Product Specification NSPG500S Y. Kawakami, et al., J. Phys. Condens. Matter 13 (2001) pp. 6993 S. F. Chichibu, Materials Science and Engineering B59 (1999) pp.298 Nikkei Electronics December 20, 2004 No. 889, page 128

  By the way, for example, a GaN-based semiconductor light-emitting element (light-emitting diode) having a blue emission wavelength, a GaN-based semiconductor light-emitting element (light-emitting diode) having a green emission wavelength, and an AlInGaP-based compound semiconductor light emission having a red emission wavelength. In an image display device configured by arranging elements (light emitting diodes) corresponding to each sub-pixel, chromaticity coordinates and luminance between pixels (pixels) are adjusted, but the number of components is increased. There is a strong demand for further widening the color reproduction range without increasing the manufacturing cost, that is, without requiring a plurality of types of light emitting elements (light emitting diodes) corresponding to many primary colors. There is a similar strong demand for a planar light source device that irradiates a liquid crystal display device from the back side.

  However, the above-mentioned patent publications and patent application publications or the above-mentioned documents have a wider color reproduction range without requiring a plurality of types of light-emitting elements (light-emitting diodes) corresponding to many primary colors. There is no specific disclosure regarding the technology to be performed.

  Accordingly, an object of the present invention is to provide an image display device incorporating a GaN-based semiconductor light-emitting element, which can further widen the color reproduction range without increasing the manufacturing cost such as an increase in the number of parts, and the like. And a liquid crystal display device assembly.

In order to achieve the above object, an image display device according to a first aspect of the present invention includes:
A first image display device including a first light emitting element that emits blue light, a second image display device including a second light emitting element that emits green light, and a third image including a third light emitting element that emits red light. An image display device comprising a display device, wherein an image is formed by blue, green and red light emitted from the first image display device, the second image display device and the third image display device,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities.

An image display device according to a second aspect of the present invention for achieving the above object is
A light-emitting element unit for displaying a color image, which is composed of a first light-emitting element that emits blue light, a second light-emitting element that emits green light, and a third light-emitting element that emits red light, is a two-dimensional matrix. An image display device comprising an array,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities.

To achieve the above object, a planar light source device of the present invention is a planar light source device that irradiates a transmissive or transflective liquid crystal display device from the back,
A first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities.

In order to achieve the above object, a liquid crystal display device assembly of the present invention includes a transmissive or transflective liquid crystal display device and a liquid crystal display device including a planar light source device that irradiates the liquid crystal display device from the back side. An assembly comprising:
The planar light source device includes a first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light.
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities.

In the image display device, the planar light source device, or the liquid crystal display assembly according to the first aspect or the second aspect of the present invention (hereinafter, these may be collectively referred to simply as the present invention). The GaN-based semiconductor light-emitting device can be essentially a GaN-based semiconductor light-emitting device having an arbitrary configuration and structure.
(A) a first GaN compound semiconductor layer having an n-type conductivity,
(B) an active layer having a multiple quantum well structure comprising a well layer and a barrier layer separating the well layer and the well layer; and
(C) a second GaN compound semiconductor layer having p-type conductivity,
With
D ₁ The well layer density of the 1GaN based compound semiconductor layer side in the active layer, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, the well in the active layer so as to satisfy d _1> d ₂ A configuration in which layers are arranged is preferable. Such a configuration may be referred to as the present invention having a well layer density changing structure for convenience.

  Here, in order to vary the well layer density, the thickness of the well layer is made constant and the thickness of the barrier layer is varied (specifically, the thickness of the barrier layer on the first GaN compound semiconductor layer side in the active layer). The thickness is preferably smaller than the thickness of the barrier layer on the second GaN-based compound semiconductor layer side). However, the present invention is not limited to this. The thickness may be different (specifically, the thickness of the well layer on the first GaN compound semiconductor layer side in the active layer is made larger than the thickness of the well layer on the second GaN compound semiconductor layer side). In addition, both the thickness of the well layer and the thickness of the barrier layer may be different.

The well layer density d ₁ and the well layer density d ₂ are defined as follows. That is, when the active layer having the total thickness t ₀ is divided into two in the thickness direction, the thickness of the active layer first region AR ₁ which is the active layer region on the first GaN compound semiconductor layer side is set to t ₁ , The thickness of the active layer second region AR ₂ , which is the active layer region on the 2GaN compound semiconductor layer side, is t ₂ (where t ₀ = t ₁ + t ₂ ). The number of well layers included in the active layer first region AR ₁ is WL ₁ (a positive number, not limited to an integer), and the number of well layers included in the active layer second region AR ₂ is WL ₂ ( It is a positive number and is not limited to an integer, and is the total number of well layers WL = WL ₁ + WL ₂ ). When one well layer (thickness t _IF ) exists across the active layer first region AR ₁ and the active layer second region AR ₂ , the well included only in the active layer first region AR ₁ . The number of layers is WL ′ ₁ , the number of well layers included only in the active layer second region AR ₂ is WL ′ _2, and the well layers straddling the active layer first region AR ₁ and the active layer second region AR _2. The thickness included in the active layer first region AR ₁ is the thickness t _IF-1 , and the thickness included in the active layer second region AR ₂ is the thickness t _IF-2 (t _IF = t _IF-1 + t _{IF -2} )
WL ₁ = WL ′ ₁ + ΔWL ₁
WL ₂ = WL ′ ₂ + ΔWL ₂
It is. However,
ΔWL ₁ + ΔWL ₂ = 1
And
WL = WL ₁ + WL ₂
= WL ' ₁ + WL' ₂ +1
ΔWL ₁ = t _IF-1 / t _IF
ΔWL ₂ = t _IF-2 / t _IF
It is.

Then, the well layer density d ₁ and the well layer density d ₂ has the following formula (1-1) can be obtained from the equation (1-2). However, k≡ (t ₀ / WL).

d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
_{= K (WL 1 / t 1} ) (1-1)
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
_{= K (WL 2 / t 2} ) (1-2)

In this case, the total thickness of the active layer is t _0, the well layer density in the active layer a first region AR ₁ up to the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (2t _0/3) d _1, when the well layer density in the active layer within the second region AR ₂ to a thickness from the 2GaN based compound semiconductor layer side interface (t _0/3) was d _2, so as to satisfy d _1> d ₂ well layer may be a configuration that is disposed in the active layer, or alternatively, the total thickness of the active layer is t _0, the thickness from the 1GaN based compound semiconductor layer side interface of the active layer of the (t _0/2 ) d ₁ of the well layer density in the active layer a first region AR ₁ to the well layer density of the 2GaN based compound semiconductor layer side thickness from the interface of (t _0/2) active layer to the second region AR ₂ the when the d _2, d _1> well layer in the active layer so as to satisfy the d ₂ is being arranged Configuration and it is possible to, alternatively, the total thickness of the active layer is t _0, the 1GaN based compound semiconductor layer side thickness from the interface of the active layer (t _0/3) to the active layer a first region AR ₁ of well layer density d ₁ of, when the thickness from the 2GaN based compound semiconductor layer side interface (2t _0/3) the well layer density in the active layer within the second region AR ₂ up to and d _2, d _1> d The well layer in the active layer may be arranged so as to satisfy ₂ .

In the present invention having the well layer density changing structure including the various preferable modes and configurations described above, d ₂ / d ₁ ≦ 0.8, preferably d ₂ / d ₁ ≦ 0.5 is satisfied. It is desirable that a well layer in the active layer is disposed on the surface.

Further, in the present invention having a well layer density changing structure including the various preferred modes and configurations described above, the GaN-based semiconductor light-emitting element is
(D) an underlayer containing In atoms formed between the first GaN-based compound semiconductor layer and the active layer, and
(E) a superlattice structure layer formed between the active layer and the second GaN-based compound semiconductor layer and containing a p-type dopant;
It can be set as the structure further provided. With such a configuration, it is possible to achieve a more stable operation of the GaN-based semiconductor light-emitting element at a high operating current density while further improving the light emission efficiency and further reducing the operating voltage.

In such a configuration, an undoped GaN-based compound semiconductor layer is formed between the active layer and the superlattice structure layer, and the thickness of the undoped GaN-based compound semiconductor layer is 100 nm or less. Is preferred. The total thickness of the superlattice structure layer is desirably 5 nm or more, and the period of the superlattice structure in the superlattice structure layer is preferably 2 atomic layers or more and 20 nm or less. The concentration of the p-type dopant contained in the superlattice structure layer is preferably 1 × 10 ¹⁸ / cm ^{3 to} 4 × 10 ²⁰ / cm ³ . Alternatively, the thickness of the underlayer is preferably 20 nm or more, and an undoped GaN-based compound semiconductor layer is formed between the underlayer and the active layer, and the thickness of the undoped GaN-based compound semiconductor layer is 50 nm. The following is desirable. Furthermore, the underlayer and the active layer contain In, the In composition ratio in the underlayer is 0.005 or more, and can be configured to be lower than the In composition ratio in the active layer. Can also be configured to contain an n-type dopant of 1 × 10 ¹⁶ / cm ^{3 to} 1 × 10 ²¹ / cm ³ .

In the present invention including the various preferable modes and configurations described above, the second light emitting element that emits green light is composed of a GaN-based semiconductor light-emitting element, and the emission wavelength of the GaN-based semiconductor light-emitting element is λ ₁ (nm). ) And λ ₂ (nm), green (510) ≦ λ ₁ ≦ 540 (nm) and 470 (nm) ≦ λ ₂ ≦ 510 (nm) are satisfied, or GaN When the emission wavelength of the semiconductor light emitting element is λ ₁ (nm), λ ₂ (nm), and λ ₃ (nm), the green color is 510 (nm) ≦ λ ₁ ≦ 540 (nm), 490 (nm). It is preferable that ≦ λ ₂ ≦ 510 (nm) and 470 (nm) ≦ λ ₃ ≦ 490 (nm) are satisfied. When a peak exists in the emission wavelength, it means the emission peak wavelength. The same applies to the following description.

Alternatively, in the present invention including the various preferable modes and configurations described above, the first light emitting element emitting blue light is composed of a GaN-based semiconductor light-emitting element, and the emission wavelength of the GaN-based semiconductor light-emitting element is λ _{When 1} (nm) and λ ₂ (nm) are satisfied, it is preferable to satisfy 430 (nm) ≦ λ ₁ ≦ 460 (nm) and 455 (nm) ≦ λ ₂ ≦ 470 (nm) which are blue. . Alternatively, it is preferable to emit light so that the y coordinate of blue chromaticity is large when the operating current density is low, and the y coordinate of blue chromaticity is small when the operating current density is high.

  In general, a semiconductor light emitting element also changes its emission wavelength due to heat generation or temperature change during characteristic measurement. Therefore, in the present invention, the characteristics at approximately room temperature (25 ° C.) are targeted. When the GaN-based semiconductor light-emitting element itself generates little heat, there is no problem with driving with a direct current, but when the heat generation is large, the temperature of the GaN-based semiconductor light-emitting element itself (such as driving with a pulse current) It is necessary to adopt a measurement method in which the temperature does not change significantly from room temperature.

  In addition, regarding the emission wavelength, the power peak wavelength in the spectrum is targeted. It is not a dominant wavelength (principal wavelength) that is used to express a spectrum that takes into account human visual characteristics or the like, or a normal hue. Furthermore, depending on the measurement conditions, light emitted from the active layer due to thin film interference or the like may be reflected many times, so that it may be observed as a spectrum with periodic fluctuations. The spectrum reflecting the light generated in the active layer from which the fluctuations are removed is considered.

Furthermore, the operating current density of the GaN-based semiconductor light-emitting element is a value obtained by dividing the operating current value by the active layer area (junction region area). That is, a commercially available GaN-based semiconductor light-emitting element has not only various package forms, but also the size of the GaN-based semiconductor light-emitting element varies depending on the application and the amount of light. In addition, it is difficult to directly compare the current value dependency of characteristics, such as a difference in standard driving current (operating current) depending on the size of the GaN-based semiconductor light emitting device. In the present invention, for the sake of generalization, not the drive current value itself but the operating current density (unit: ampere / cm ² ) obtained by dividing such a drive current value by the active layer area (junction region area). Express.

In the present invention having the well layer density changing structure including the various preferable forms and configurations described above, the active layer contains indium atoms, more specifically, Al _x Ga _{1− xy} In _y N (where x ≧ 0, y> 0, 0 <x + y ≦ 1). Examples of the first GaN compound semiconductor layer and the second GaN compound semiconductor layer include a GaN layer, an AlGaN layer, an InGaN layer, and an AlInGaN layer. Furthermore, these compound semiconductor layers may contain boron (B) atoms, thallium (Tl) atoms, arsenic (As) atoms, phosphorus (P) atoms, and antimony (Sb) atoms.

  Furthermore, in the present invention having the well layer density changing structure including the various preferable modes and configurations described above, the number of well layers (WL) in the active layer is 2 or more, preferably 4 or more. This is preferable from the viewpoint of more surely shifting the emission wavelength as the operating current density increases without sacrificing the luminous efficiency.

  In the present invention, at least one (one type) of the first light emitting element, the second light emitting element, and the third light emitting element is constituted by a GaN-based semiconductor light emitting element. In other words, any one of the first light-emitting element, the second light-emitting element, and the third light-emitting element is formed of a GaN-based semiconductor light-emitting element, and the remaining two types of light-emitting elements have other configurations. The light emitting element may be composed of a semiconductor light emitting element, or any one of the first light emitting element, the second light emitting element, and the third light emitting element is composed of a GaN-based semiconductor light emitting element, and the remaining one type The light emitting element may be composed of a semiconductor light emitting element of another configuration, or all of the light emitting elements of the first light emitting element, the second light emitting element, and the third light emitting element are composed of a GaN-based semiconductor light emitting element. Also good. An example of a semiconductor light emitting device having another configuration is an AlGaInP semiconductor light emitting device that emits red light.

  Examples of the image display device according to the first aspect of the present invention include an image display device having the configuration and structure described below. Unless otherwise specified, the number of light emitting elements constituting the image display device or the light emitting element panel may be determined based on specifications required for the image display device. Further, based on the specifications required for the image display device, a configuration in which a light valve is further provided can be adopted.

(1) Image display device according to aspect 1A ...
(Α) a first image display device including a first light emitting element panel in which first light emitting elements emitting blue light are arranged in a two-dimensional matrix;
(Β) a second image display device including a second light emitting element panel in which first light emitting elements emitting green light are arranged in a two-dimensional matrix; and
(Γ) a third image display device including a third light emitting element panel in which first light emitting elements emitting red light are arranged in a two-dimensional matrix; and
(Δ) Means for collecting light emitted from the first image display device, the second image display device, and the third image display device into one optical path (for example, a dichroic prism; the same applies to the following description) ),
With
A color display image display device (direct view type or projection type) that controls the light emitting / non-light emitting states of the first light emitting element, the second light emitting element, and the third light emitting element.
(2) Image display device according to aspect 1B ...
(Α) a first light emitting element that emits blue light, and a first light passage control device that controls passage / non-passage of light emitted from the first light emitting element that emits blue light [a kind of light valve For example, a liquid crystal display device, a digital micromirror device (DMD), LCOS (Liquid Crystal On Silicon), and the same in the following description.]
(Β) From a second light emitting element that emits green light and a second light passage control device (light valve) for controlling passage / non-passage of light emitted from the second light emitting element that emits green light A second image display device comprising:
(Γ) From a third light emitting device that emits red light and a third light passage control device (light valve) for controlling passage / non-passage of light emitted from the third light emitting device that emits red light A third image display device comprising:
(Δ) means for collecting light that has passed through the first light passage control device, the second light passage control device, and the third light passage control device into one optical path;
With
A color display image display device (direct view type or projection type) that displays an image by controlling passage / non-passage of light emitted from these light emitting elements by a light passage control device. The number of the first light emitting element, the second light emitting element, and the third light emitting element may be determined based on specifications required for the image display device, and may be one or a plurality. Further, as means (light guide member) for guiding the emitted light emitted from the first light emitting element, the second light emitting element, and the third light emitting element to the light passage control device, a light guide member, a microlens array, a mirror Examples thereof include a reflector, a condenser lens, and the like.
(3) Image display device according to aspect 1C ...
(Α) A first light emitting element panel in which first light emitting elements emitting blue light are arranged in a two-dimensional matrix, and a blue color for controlling passage / non-passage of light emitted from the first light emitting element panel A first image display device comprising a light passage control device (light valve);
(Β) A second light emitting element panel in which second light emitting elements emitting green light are arranged in a two-dimensional matrix, and a green color for controlling passage / non-passage of light emitted from the second light emitting element panel. A second image display device comprising a light passage control device (light valve);
(Γ) A third light emitting element panel in which third light emitting elements emitting red light are arranged in a two-dimensional matrix, and a red color for controlling passage / non-passage of light emitted from the third light emitting element panel. A third image display device comprising a light passage control device (light valve), and
(Δ) comprises means for collecting light that has passed through the blue light passage control device, the green light passage control device, and the red light passage control device into one optical path;
A color for displaying an image by controlling passage / non-passage of the emitted light emitted from the first light emitting element panel, the second light emitting element panel, and the third light emitting element panel by a light passage control device (light valve). Display image display device (direct view type or projection type).
(4) Image display device according to aspect 1D ...
(Α) a first image display device including a first light emitting element that emits blue light;
(Β) a second image display device including a second light emitting element that emits green light, and
(Γ) a third image display device including a third light emitting element that emits red light, and
(Δ) means for collecting the light emitted from the first image display device, the second image display device, and the third image display device into one optical path;
(Ε) a light passage control device (light valve) for controlling the passage / non-passage of the light emitted from the means for collecting in one light path;
With
A field-sequential color display image display device (direct view type or projection type) that displays an image by controlling passage / non-passage of light emitted from these light emitting elements by a light passage control device.
(5) Image display device according to aspect 1E ...
(Α) a first image display device including a first light emitting element panel in which first light emitting elements emitting blue light are arranged in a two-dimensional matrix;
(Β) a second image display device including a second light emitting element panel in which second light emitting elements emitting green light are arranged in a two-dimensional matrix; and
(Γ) a third image display device comprising a third light emitting element panel in which third light emitting elements emitting red light are arranged in a two-dimensional matrix, and
(Δ) means for collecting light emitted from each of the first image display device, the second image display device, and the third image display device into one optical path;
(Ε) a light passage control device (light valve) for controlling the passage / non-passage of the light emitted from the means for collecting in one light path;
With
A field sequential color display image display device (direct view type or projection type) that displays an image by controlling passage / non-passage of the light emitted from these light emitting element panels by a light passage control device.

  Further, examples of the image display apparatus according to the second aspect of the present invention include an image display apparatus having a configuration and structure described below. The number of light emitting element units may be determined based on specifications required for the image display device. Further, based on the specifications required for the image display device, a configuration in which a light valve is further provided can be adopted.

(1) Image display device according to aspect 2A ...
A passive matrix type that displays an image by directly viewing the light emitting state of each light emitting element by controlling the light emitting / non-light emitting state of each of the first light emitting element, the second light emitting element, and the third light emitting element. Alternatively, an active matrix type direct-view type color display image display device.
(2) Image display apparatus according to aspect 2B ...
Control the light emitting / non-light emitting state of each of the first light emitting element, the second light emitting element, and the third light emitting element, and project the image onto the screen to display an image, a passive matrix type or active matrix type projection type, color display Image display device.
(3) Image display device according to aspect 2C ...
A light passage control device (light valve) for controlling passage / non-passage of light emitted from the light emitting element units arranged in a two-dimensional matrix is provided, and includes a first light emitting element and a second light emitting element in the light emitting element unit. The light emitting / non-light emitting state of each of the light emitting element and the third light emitting element is controlled in a time-sharing manner, and the light passing through the first light emitting element, the second light emitting element, and the third light emitting element is passed by the light passage control device. / Field sequential color display image display device (direct view type or projection type) that displays images by controlling non-passage.

  The planar light source device of the present invention or the planar light source device in the liquid crystal display device assembly of the present invention has two types of planar light source devices (backlights), for example, Japanese Utility Model Laid-Open Nos. 63-187120 and 2002. The direct-type planar light source device disclosed in JP-A-277870 and the edge light type (also referred to as sidelight type) planar light source device disclosed in, for example, JP-A-2002-131552 can be used. The number of light emitting elements is essentially arbitrary and may be determined based on specifications required for the planar light source device. In addition, the number of the first light emitting element, the second light emitting element, and the third light emitting element that constitute the light source in the planar light source device may be one or plural.

  Here, in the direct type planar light source device, the first light emitting element, the second light emitting element, and the third light emitting element are arranged facing the liquid crystal display device, and the liquid crystal display device, the first light emitting element, Between the second light emitting element and the third light emitting element, an optical function sheet group such as a diffusion plate, a diffusion sheet, a prism sheet, and a polarization conversion sheet, and a reflection sheet are arranged.

  In the direct type planar light source device, more specifically, a first light emitting element that emits blue light (for example, mainly having a wavelength of 450 nm) and a second light emission that emits green light (for example, mainly having a wavelength of 530 nm). The element and the third light emitting element that emits red light (for example, mainly 640 nm in wavelength) can be arranged and arranged in the housing, but the present invention is not limited to this. Here, when a plurality of first light emitting elements that emit blue light, a plurality of second light emitting elements that emit green light, and a plurality of third light emitting elements that emit red light are arranged and arranged in a housing, As an arrangement state of these light emitting elements, a plurality of light emitting element arrays each including a blue light emitting first light emitting element, a green light emitting second light emitting element, and a red light emitting third light emitting element are arranged in the horizontal direction of the screen of the liquid crystal display device. The light emitting element array can be formed in a row, and a plurality of light emitting element arrays can be arranged in the vertical direction of the screen of the liquid crystal display device. In addition, as the light emitting element row, (one blue light emitting first light emitting element, one green light emitting second light emitting element, one red light emitting third light emitting element), (one blue light emitting first light emitting element, Two green light emitting second light emitting elements, one red light emitting third light emitting element), (one blue light emitting first light emitting element, two green light emitting second light emitting elements, and two red light emitting third light emitting elements). A plurality of combinations such as (element) can be given. In addition, you may further provide the light emitting element which light-emits 4th color other than red, green, and blue. In addition, for example, a light extraction lens described in page 128 of Nikkei Electronics No. 889, No. 889, may be attached to the light emitting element.

  On the other hand, in the edge light type planar light source device, a light guide plate is disposed facing the liquid crystal display device, and a light emitting element is disposed on a side surface (first side surface described below) of the light guide plate. The light guide plate includes a first surface (bottom surface), a second surface (top surface) facing the first surface, a first side surface, a second side surface, a third side surface facing the first side surface, and a second side surface. It has the 4th side which countered. As a more specific shape of the light guide plate, a wedge-shaped truncated quadrangular pyramid shape can be cited as a whole. In this case, two opposing side surfaces of the truncated quadrangular pyramid correspond to the first surface and the second surface. The bottom surface of the truncated quadrangular pyramid corresponds to the first side surface. And it is desirable for the surface part of the 1st surface (bottom surface) to provide the convex part and / or the recessed part. Light is incident from the first side surface of the light guide plate, and light is emitted from the second surface (top surface) toward the liquid crystal display device. Here, the second surface of the light guide plate may be smooth (that is, may be a mirror surface), or may be provided with a blast texture having a diffusion effect (that is, a fine uneven surface).

  It is desirable that the first surface (bottom surface) of the light guide plate is provided with a convex portion and / or a concave portion. That is, it is desirable that the first surface of the light guide plate is provided with a convex portion, or a concave portion, or an uneven portion. When the concavo-convex portion is provided, the concave portion and the convex portion may be continuous or discontinuous. The convex portions and / or concave portions provided on the first surface of the light guide plate are configured to be continuous convex portions and / or concave portions extending along a direction forming a predetermined angle with the light incident direction to the light guide plate. Can do. In such a configuration, a triangle or square is used as a continuous convex or concave cross-sectional shape when the light guide plate is cut in a virtual plane perpendicular to the first surface in the light incident direction to the light guide plate. Any smooth curve can be exemplified, including any rectangle, including rectangle, trapezoid; any polygon; circle, ellipse, parabola, hyperbola, catenary and the like. The direction forming a predetermined angle with the light incident direction on the light guide plate means a direction of 60 to 120 degrees when the light incident direction on the light guide plate is 0 degree. The same applies to the following. Alternatively, the convex portion and / or concave portion provided on the first surface of the light guide plate is a discontinuous convex portion and / or concave portion extending along a direction forming a predetermined angle with the light incident direction to the light guide plate. It can be configured. In such a configuration, as a discontinuous convex shape or concave shape, a pyramid, a cone, a cylinder, a polygonal column including a triangular column or a quadrangular column, a part of a sphere, a part of a spheroid, a rotating parabola Various smooth curved surfaces such as a part of a body and a part of a rotating hyperbola can be exemplified. In the light guide plate, in some cases, a convex portion or a concave portion may not be formed on the peripheral portion of the first surface. Furthermore, the light emitted from the light source and incident on the light guide plate collides with the convex portion or concave portion formed on the first surface of the light guide plate and is scattered, but the convex portion provided on the first surface of the light guide plate. Alternatively, the height, depth, pitch, and shape of the recesses may be constant or may be changed as the distance from the light source increases. In the latter case, for example, the pitch of the convex portion or the concave portion may be made finer as the distance from the light source increases. Here, the pitch of the convex portions or the pitch of the concave portions means the pitch of the convex portions or the pitch of the concave portions along the light incident direction to the light guide plate.

  In the planar light source device including the light guide plate, it is desirable to dispose the reflection member so as to face the first surface of the light guide plate. A liquid crystal display device is disposed to face the second surface of the light guide plate. The light emitted from the light source enters the light guide plate from the first side surface of the light guide plate (for example, the surface corresponding to the bottom surface of the truncated quadrangular pyramid), collides with the convex portion or the concave portion of the first surface, and is scattered. The light is emitted from the first surface, is reflected by the reflecting member, is incident on the first surface again, is emitted from the second surface, and irradiates the liquid crystal display device. For example, a diffusion sheet or a prism sheet may be disposed between the liquid crystal display device and the second surface of the light guide plate. Further, the light emitted from the light source may be guided directly to the light guide plate or indirectly guided to the light guide plate. In the latter case, for example, an optical fiber may be used.

  The light guide plate is preferably made of a material that does not absorb much light emitted from the light source. Specifically, examples of the material constituting the light guide plate include glass and plastic materials (for example, PMMA, polycarbonate resin, acrylic resin, amorphous polypropylene resin, and styrene resin including AS resin). be able to.

  For example, a transmissive color liquid crystal display device is disposed, for example, between a front panel having a transparent first electrode, a rear panel having a transparent second electrode, and a front panel and a rear panel. Made of liquid crystal material.

  Here, more specifically, the front panel is, for example, a first substrate made of a glass substrate or a silicon substrate, and a transparent first electrode (also called a common electrode) provided on the inner surface of the first substrate. For example, it is made of ITO) and a polarizing film provided on the outer surface of the first substrate. Furthermore, the front panel has a configuration in which a color filter covered with an overcoat layer made of acrylic resin or epoxy resin is provided on the inner surface of the first substrate, and a transparent first electrode is formed on the overcoat layer. have. An alignment film is formed on the transparent first electrode. Examples of the color filter arrangement pattern include a delta arrangement, a stripe arrangement, a diagonal arrangement, and a rectangle arrangement. On the other hand, the rear panel more specifically includes, for example, a second substrate made of a glass substrate or a silicon substrate, a switching element formed on the inner surface of the second substrate, and conduction / non-conduction by the switching element. A transparent second electrode to be controlled (also called a pixel electrode, which is made of, for example, ITO) and a polarizing film provided on the outer surface of the second substrate. An alignment film is formed on the entire surface including the transparent second electrode. Various members and liquid crystal materials constituting these transmissive color liquid crystal display devices can be composed of known members and materials. Examples of the switching element include a three-terminal element such as a MOS type FET and a thin film transistor (TFT) formed on a single crystal silicon semiconductor substrate, and a two-terminal element such as an MIM element, a varistor element, and a diode.

  In the present invention having the well layer density changing structure including various preferable modes and configurations described above, various GaN-based compound semiconductor layers such as a first GaN-based compound semiconductor layer, an active layer, and a second GaN-based compound semiconductor layer are formed. Examples of the method include a metal organic chemical vapor deposition method (MOCVD method), an MBE method, and a hydride vapor deposition method in which halogen contributes to transport or reaction.

Examples of the organic gallium source gas in the MOCVD method include trimethyl gallium (TMG) gas and triethyl gallium (TEG) gas, and examples of the nitrogen source gas include ammonia gas and hydrazine gas. In forming the first GaN-based compound semiconductor layer having the n-type conductivity, for example, silicon (Si) may be added as an n-type impurity (n-type dopant), and the first GaN-based compound semiconductor layer having the p-type conductivity may be used. In forming the 2GaN compound semiconductor layer, for example, magnesium (Mg) may be added as a p-type impurity (p-type dopant). Further, when aluminum (Al) or indium (In) is included as a constituent atom of the GaN-based compound semiconductor layer, trimethylaluminum (TMA) gas may be used as the Al source, and trimethylindium (TMI) gas is used as the In source. Use it. Furthermore, monosilane gas (SiH ₄ gas) may be used as the Si source, and cyclopentadienyl magnesium gas, methylcyclopentadienyl magnesium, or biscyclopentadienyl magnesium (Cp ₂ Mg) may be used as the Mg source. . In addition to Si, Ge, Se, Sn, C, and Ti can be cited as n-type impurities (n-type dopants). As p-type impurities (p-type dopants), Zn, Cd, Examples include Be, Ca, Ba, and O.

  The p-type electrode connected to the second GaN compound semiconductor layer having the p-type conductivity is palladium (Pd), platinum (Pt), nickel (Ni), Al (aluminum), Ti (titanium), gold (Au ) And at least one metal selected from the group consisting of silver (Ag), preferably having a single layer configuration or a multilayer configuration, or a transparent conductive material such as ITO (Indium Tin Oxide) In particular, it is preferable to use silver (Ag), Ag / Ni, or Ag / Ni / Pt that can reflect light with high efficiency. On the other hand, the n-type electrode connected to the first GaN compound semiconductor layer having the n-type conductivity is gold (Au), silver (Ag), palladium (Pd), Al (aluminum), Ti (titanium), tungsten. It is desirable to have a single layer configuration or a multilayer configuration including at least one metal selected from the group consisting of (W), Cu (copper), Zn (zinc), tin (Sn), and indium (In), For example, Ti / Au, Ti / Al, Ti / Pt / Au can be exemplified. An n-type electrode and a p-type electrode can be formed by PVD methods, such as a vacuum evaporation method and sputtering method, for example.

  A pad electrode may be provided on the n-type electrode or the p-type electrode for electrical connection with an external electrode or circuit. The pad electrode has a single-layer configuration or a multi-layer configuration including at least one metal selected from the group consisting of Ti (titanium), aluminum (Al), Pt (platinum), Au (gold), and Ni (nickel). It is desirable to have. Alternatively, the pad electrode may have a multilayer configuration exemplified by a multilayer configuration of Ti / Pt / Au and a multilayer configuration of Ti / Au.

  In the present invention including the preferable modes and configurations described above, the assembly of the light emitting element may have a face-up structure or a flip chip structure.

  In the present invention, a method is employed in which the emission wavelength of the GaN-based semiconductor light-emitting element is controlled at the operating current density (more specifically, the peak current value of the drive current) as described above. In the present invention, the light emission amount of the GaN-based semiconductor light-emitting element can be controlled by controlling the pulse width of the driving current, or can be controlled by controlling the pulse density of the driving current. These can be performed in combination. The time period of the peak current value of the drive current is preferably 10 milliseconds or less (100 Hz or more) in order to suppress flicker.

Specifically, for example, in one type of GaN-based semiconductor light emitting device, the peak current value of the drive current when obtaining a certain emission wavelength λ ₁ is I ₁ , the pulse width of the drive current is P ₁ , and the emission wavelength λ _2. The peak current value of the drive current when obtaining (≠ λ ₁ ) is I ₂ (≠ I ₁ ), the pulse width of the drive current is P ₂ , and the GaN-based semiconductor light emitting device is driven at the peak current value I _1. , its subsequent, referred to as a one pulse period T _P and overall driving at the peak current value I _2, the image display device incorporated the GaN-based semiconductor light-emitting device, a surface light source device, a GaN in a liquid crystal display device assembly When one operation cycle of the operation of the semiconductor light emitting element is T _OP ,
(1) By controlling the peak current value I ₁ and the peak current value I ₂ of the drive current, the emission wavelength λ of the light emitted from the GaN-based semiconductor light-emitting element can be controlled,
(2) By controlling the pulse width P ₁ and the pulse width P ₂ of the drive current (pulse width control of the drive current), the emission color as a whole of the light emitted from the GaN-based semiconductor light-emitting element [with two types of wavelengths Different emission colors (that is, two types of light), or a combination of one type of emission color and an emission color in which two types of emission colors having different wavelengths are mixed (that is, two types of light), or two types The combination of the luminescent color having a different wavelength and the luminescent color obtained by mixing two types of luminescent colors (that is, three types of light)] can be controlled,
(3) (pulse width control of driving current) by controlling the length of one pulse period T _P of the GaN-based semiconductor light-emitting element (pulse width), the light emission amount of the light emitted from the GaN-based semiconductor light-emitting device (Brightness , Brightness) and / or
(3 ') (pulse density control of driving current) by controlling the number (pulse density) in one pulse period T _P in one operation during period T _OP of the operation of the GaN-based semiconductor light-emitting device, the GaN-based semiconductor light-emitting element The amount of emitted light (brightness and luminance) can be controlled. In the above description, although two types of emission wavelengths λ ₁ and λ ₂ are used, it goes without saying that the present invention can also be applied to three or more types of emission wavelengths.

In addition, the simultaneous control of the light emission wavelength and the light emission amount of the GaN-based semiconductor light emitting element described above is, for example,
(A) a pulse driving current supply means for supplying a pulse driving current to the GaN-based semiconductor light-emitting device; and
(B) pulse driving current setting means for setting the pulse width and pulse density of the pulse driving current;
This can be achieved by a drive circuit for a GaN-based semiconductor light-emitting device comprising: The driving circuit for the GaN-based semiconductor light-emitting device can be applied not only to the GaN-based semiconductor light-emitting device according to the present invention having a well layer density changing structure characterized by the well layer density, but also to a conventional GaN-based semiconductor light-emitting device. It can also be applied to semiconductor light emitting devices.

  In the present invention, it is possible to display four or more colors just by preparing three types of light emitting elements for displaying three primary colors (RGB) as in the conventional case. That is, a color gamut larger than 120% can be expressed by the NTSC ratio, a color gamut larger than 130% can be expressed by the NTSC ratio, and a color gamut larger than 140% by the NTSC ratio can be expressed. Can be expressed. Therefore, for example, when priority is given to brightness or when displaying a conventional video source, one or more colors are displayed in addition to the three primary colors if the color reproduction range is to be expanded. Both can be easily switched by controlling the operating current density (specifically, for example, a drive current waveform). Further, the light emitting element to be used is not wasted in any display, which is useful for reducing the number of parts and cost.

In the present invention, d ₁ the well layer density of the 1GaN based compound semiconductor layer side in the active layer, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, satisfies d _1> d ₂ By disposing the well layer in the active layer as described above, the emission wavelength can be greatly shifted as the operating current density increases without reducing the light emission efficiency. According to the experiments by the present inventors, in the GaN-based semiconductor light-emitting device, it is found that the well layer contributing to light emission gradually shifts to the well layer on the second GaN-based compound semiconductor layer side as the current density increases. It was. Therefore, if more well layers are allocated to positions that contribute to light emission at a low current density, the carrier concentration per well layer involved in light emission can be reduced, and positions that contribute to light emission at a high current density. If a small number of well layers are distributed, the carrier concentration per well layer involved in light emission can be increased. That is, even if the change width of the operating current density is the same, the change width of the carrier density per well layer involved in light emission can be made larger than when the well layers are evenly distributed. The main factors of the wavelength shift in the GaN-based semiconductor light-emitting device are the band filling of the local emission center and the Coulomb shielding effect by the piezoelectric field, which are sensitive to the carrier concentration. In other words, by adopting the above-described structure in the GaN-based semiconductor light-emitting element, even when the operating current density changes, the GaN-based semiconductor light-emitting element is more involved in light emission than when the well layers are evenly distributed in the active layer. The change width of the carrier density per well layer can be further increased, whereby the wavelength shift can be further increased. Therefore, the emission wavelength can be adjusted and controlled based on the control of the operating current density (or drive current), and a large wavelength shift can be realized with a small current peak change width in the case of multicolor emission. it can.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

  Example 1 relates to an image display apparatus according to a first aspect of the present invention. Hereinafter, the image display device of Example 1 will be described. Prior to that, the characteristics of a GaN-based light emitting diode having a conventional structure were examined. The standard value of the operating current value varies depending on the active layer area (junction area) of the light emitting diode. For example, the operating current value of a GaN-based light emitting diode having an active layer area (junction region area) of 300 to 350 μm square is about 20 mA, and the operation of a GaN-based light emitting diode having an active layer area (junction region area) of 1 mm square. The current value is about 350 mA. Therefore, in order to generalize, the following description will be made using the operating current density which is a value obtained by dividing the operating current value by the active layer area (junction region area).

27 and 28 plot the emission peak wavelength against the driving current density of the GaN-based light emitting diode that emits blue light and the GaN-based light emitting diode that emits green light. In a GaN-based light emitting diode that emits blue light, there is a slight wavelength shift due to an increase in drive current density, but the luminescent color is not significantly changed. On the other hand, it can be seen that GaN-based light emitting diodes emitting green light largely shift to the short wavelength side as the drive current density increases. The emission peak wavelength at a driving current density of 30 A / cm ² is green at approximately 520 nm, but the emission peak wavelength at 600 A / cm ² is emerald at 500 nm, and the emission peak wavelength at 3 kA / cm ² is blue-green at 484 nm. It is.

  The image display apparatus of Example 1 includes a first image display apparatus including a first light emitting element 1B that emits blue light, a second image display apparatus including a second light emitting element 1G that emits green light, and red light emission. The third image display device is provided with a third light emitting element 1R, and an image is generated by blue, green, and red light emitted from the first image display device, the second image display device, and the third image display device. Is an image display device in which is formed. At least one of the first light emitting element 1B, the second light emitting element 1G, and the third light emitting element 1B is composed of a GaN-based semiconductor light-emitting element 1A. It emits light of different wavelengths based on different operating current densities.

Specifically, the image display apparatus according to the first embodiment relates to the image display apparatus according to the aspect 1A, and as illustrated in a conceptual diagram in FIG.
(Α) a first image display device including a first light emitting element panel 50B in which first light emitting elements 1B emitting blue light are arranged in a two-dimensional matrix;
(Β) a second image display device including a second light emitting element panel 50G in which the second light emitting elements 1G emitting green light are arranged in a two-dimensional matrix, and
(Γ) a third image display device including a third light emitting element panel 50R in which the third light emitting elements 1R emitting red light are arranged in a two-dimensional matrix, and
(Δ) Blue light emitted from the first light emitting element panel 50B (first image display device), the second light emitting element panel 50G (second image display device), and the third light emitting element panel 50R (third image display device); Means (for example, dichroic prism 57) for collecting green and red light into one optical path;
A direct-view type or a projection type of color display for controlling the light emitting / non-light emitting states of the first light emitting element 1B for blue light emission, the second light emitting element 1G for green light emission and the third light emitting element 1R for red light emission. This is an image display device. Here, more specifically, the light emitted from the light emitting element panels 50R, 50G, and 50B is incident on the dichroic prism 57, and the optical paths of these lights are combined into a single optical path for direct view image display. In the apparatus, the image is directly viewed, or in the projection type image display apparatus, the image is projected onto the screen via the projection lens 56.

  Unless otherwise specified, the number of light emitting elements constituting the light emitting element panel or the image display apparatus may be determined based on the specifications required for the image display apparatus. The same applies to the following embodiments. Further, for the description of the light emitting element panels 50R, 50G, and 50B, these are simply referred to as the light emitting element panel 50, and for the description of the light emitting elements 1B, 1G, and 1R, these are simply collectively referred to as the light emitting element. Sometimes called 1. In addition, when the constituent elements of the light emitting element panel 50 are described, description will be made using reference numerals. However, regarding the constituent elements of the light emitting element panels 50B, 50G, and 50R, the reference numerals “B”, “G”, “ What is necessary is just to replace with "R".

  For example, a circuit diagram including a passive matrix light-emitting element panel is shown in FIG. 2A, and a schematic cross-sectional view of a light-emitting element panel in which the light-emitting elements 1 are arranged in a two-dimensional matrix is shown in FIG. ), One electrode (p-type electrode or n-type electrode) of each light-emitting element 1 is connected to a column driver 41, and the other electrode (n-type electrode or p-type electrode) of each light-emitting element 1 is connected to a row. -It is connected to the driver 42. The light emission / non-light emission state of each light emitting element 1 is controlled by, for example, the row driver 42, and a drive current for driving each light emitting element 1 is supplied from the column driver 41. One of the functions of the column driver 41 is the same as the function of the drive circuit 26 described later. Since the selection and driving of each light emitting element 1 can be a well-known method, detailed description is omitted.

  For example, FIG. 3 shows a circuit diagram including an active matrix type light emitting element panel. One electrode (p-type electrode or n-type electrode) of each light emitting element 1 is connected to a driver 45, The column driver 43 and the row driver 44 are connected. The other electrode (n-type electrode or p-type electrode) of each light-emitting element 1 is connected to a ground line. The light emitting / non-light emitting state of each light emitting element 1 is controlled by, for example, selection of the driver 45 by the row driver 44, and a luminance signal for driving each light emitting element 1 is supplied from the column driver 43 to the driver 45. The A predetermined voltage is separately supplied to each driver 45 from a power source (not shown), and the driver 45 supplies a drive current (based on PDM control or PWM control) corresponding to the luminance signal to the light emitting element 1. One of the functions of the column driver 43 is the same as the function of the drive circuit 26 described later. Since the selection and driving of each light emitting element 1 can be a well-known method, detailed description is omitted.

  The light emitting element panel 50 is formed on, for example, a support 51 made of a printed wiring board, the light emitting element 1 attached to the support 51, and the support 51, and one electrode (p-type electrode or n-type) of the light emitting element 1. The X direction wiring 52 connected to the column driver 41 or the row driver 42 and the other electrode (n-type electrode or p-type electrode) of the light emitting element 1. And a Y-direction wiring 53 connected to the row driver 42 or the column driver 41, a transparent base material 54 covering the light emitting element 1, and a microlens 55 provided on the transparent base material 54. Yes. However, the light emitting element panel 50 is not limited to such a configuration.

  In Example 1, the first light-emitting element 1B that emits blue light and the second light-emitting element 1G that emits green light are composed of GaN-based semiconductor light-emitting elements (GaN-based semiconductor light-emitting diodes) and emit red light. The third light emitting element 1R is composed of an AlInGaP-based compound semiconductor light emitting diode. Then, the GaN-based semiconductor light-emitting element 1A constituting the second light-emitting element 1G that emits green light emits light of different wavelengths based on different operating current densities. The first light emitting element 1B that emits blue light emits light of a certain wavelength based on a certain operating current density. That is, the image display apparatus according to the first embodiment can display four types of colors only by preparing three types of light emitting elements 1B, 1G, and 1R for displaying three primary colors (RGB).

Specifically, λ ₁ = 520 nm (green), where λ ₁ (nm) and λ ₂ (nm) are the emission wavelengths of the GaN-based semiconductor light emitting device 1A constituting the second light emitting device 1G that emits green light, λ ₂ = 484 nm (blue green). FIG. 29 illustrates the relationship between the emission intensity and the emission wavelength.

  Here, the first light emitting element 1B composed of a blue light emitting GaN based semiconductor light emitting element, the second light emitting element 1G composed of a green light emitting GaN based semiconductor light emitting element, and the third light emitting composed of a red light emitting AlGaInP based semiconductor light emitting element. FIG. 5 shows a color reproduction range (chromaticity diagram) when the element 1R is driven by the pulse current schematically shown in FIG. In the example shown in FIGS. 4 and 5, a first light emitting element 1B made of a blue light emitting GaN-based semiconductor light emitting element, a second light emitting element 1G made of a green light emitting GaN semiconductor light emitting element, and a red light emitting element. Each of the third light emitting elements 1R made of an AlGaInP-based semiconductor light emitting element emits one color. In this state, the NTSC standard (shown by a broken line) is almost completely expressed, and the NTSC ratio is 119%.

Also, a first light emitting element 1B made of a blue light emitting GaN-based semiconductor light emitting element, a second light emitting element 1G made of a green light emitting GaN semiconductor light emitting element, and a third light emitting element made of a red light emitting AlGaInP semiconductor light emitting element. FIG. 7 shows a color reproduction range (chromaticity diagram) when 1R is driven by the pulse current schematically shown in FIG. In the example shown in FIGS. 6 and 7, each of the first light emitting element 1B composed of a blue light emitting GaN-based semiconductor light emitting element and the third light emitting element 1R composed of a red light emitting AlGaInP based semiconductor light emitting element, One color is emitted. On the other hand, as described above, the second light emitting element 1G composed of a green light emitting GaN-based semiconductor light emitting element only emits the original green light (emission wavelength λ ₁ = 520 nm) (indicated as “GL” in FIG. 7). In addition, blue-green (emission wavelength λ ₂ = 484 nm) is also emitted (indicated as “GH” in FIG. 7). The green light emission and the blue-green light emission are not simultaneously but time-division, and the period of these light emission (see P ₁ and P ₂ in FIG. 12B) should be 10 milliseconds or less. Thus, flicker can be reduced. As described above, a wide color gamut can be realized as shown in FIG. 7 by appropriately setting the peak value of the pulse driving current for driving the green-emitting GaN-based semiconductor light emitting device 1G. In this state, the NTSC ratio is 142%.

Furthermore, the first light emitting device 1B made of a blue light emitting GaN-based semiconductor light emitting device emits light of different wavelengths based on different operating current densities, that is, only the original blue light (emission wavelength λ ₁ = 460 nm) is emitted. In addition, by emitting blue light (emission wavelength λ ₂ = 455 nm), a wider color gamut can be realized as shown in FIG.

The color gamut has different chromaticity points depending on various standards. For example, blue in the NTSC standard is (0.14, 0.08), but in the EBU standard, it is (0.15, 0.06). If the color purity of the blue-emitting GaN-based semiconductor light-emitting device is sufficiently high, the coordinates that include both standards can be selected as chromaticity. Due to the crystal quality of semiconductor light emitting devices, it is usually very difficult to completely satisfy both standards. In such a case, as described above, in the same blue light emitting GaN-based semiconductor light emitting device, by controlling the operating current density, it is possible not only to emit blue light close to the NTSC standard blue, but also high operating current. By driving with density, the wavelength can be shortened, and blue light close to EBU standard blue light can be emitted. Since the desired and wide color reproduction range can be realized immediately by simply changing the operating current density in this way, it is of course possible to select either one of the color reproduction ranges as well as by time-division driving or the like. Multi- _primary color emission (for example, R, G, B ₁ , B ₂ ) that emits various types of blue light can be performed, and at the same time, the NTSC standard and the EBU standard can be satisfied.

Further, a first light emitting element 1B composed of a blue light emitting GaN-based semiconductor light emitting element, a second light emitting element 1G composed of a green light emitting GaN based semiconductor light emitting element, and a third light emitting element composed of a red light emitting AlGaInP based semiconductor light emitting element. FIG. 10 shows a color reproduction range (chromaticity diagram) when the element 1R is driven by the pulse current schematically shown in FIG. In the example shown in FIGS. 9 and 10, the third light emitting element 1R made of a red light emitting AlGaInP semiconductor light emitting element emits one color. On the other hand, the second light emitting element 1G composed of a green light emitting GaN-based semiconductor light emitting element not only emits green light (emission wavelength λ ₁ = 520 nm) but also blue green (emission wavelength λ ₃ = 484 nm) and emerald. The color (emission wavelength λ ₂ = 500 nm) also emits light. The first light emitting element 1B made of a blue light emitting GaN-based semiconductor light emitting element emits not only the original blue light (emission wavelength λ ₁ = 460 nm) but also blue light (emission wavelength λ ₂ = 455 nm). . As a result, a wider color gamut can be realized as shown in FIG. In this state, the NTSC ratio is 150%.

  When using multiple colors in this way, the conventional technique requires a plurality of types of light emitting diodes corresponding to each color, but in Example 1, there are three types of light emitting diodes, that is, ordinary light emitting diodes. Only a light emitting diode emitting red light, a light emitting diode emitting green light, and a light emitting diode emitting blue light may be prepared. Further, when the light emitting diodes for each color are individually prepared for multiple colors, they are not used because they are not used in the normal three primary color display, but in the first embodiment, in the case of the three primary color display, there are three. Since it is used as a primary color light source, it is not wasted. In other words, by preparing three types of light emitting diodes for displaying three primary colors, when priority is given to brightness or when displaying a conventional video source, three primary colors and four or more colors should be used to expand the color reproduction range. Both can be displayed and can be easily switched by the drive current waveform. In other words, in the case of an image based on the three primary colors of red / green / blue, the three primary colors remain as they are, and color matching with a printing medium or particularly impressive blue-green (new green or marine blue, For example, when emphasizing emerald color or dark blue color), it is possible to switch to four primary colors or more. Further, the light emitting diode to be used is not wasted in any display, which helps to reduce the number of parts and the cost. As the red light emitting semiconductor light emitting element, in addition to the AlGaInP based semiconductor light emitting element, a GaN based semiconductor light emitting element can also be used. The same applies to the following embodiments.

Here, the GaN-based semiconductor light-emitting element (light-emitting diode) 1A can be essentially a GaN-based semiconductor light-emitting element having an arbitrary configuration and structure. In Example 1,
(A) a first GaN compound semiconductor layer 13 having n-type conductivity,
(B) an active layer 15 having a multiple quantum well structure including a well layer and a barrier layer separating the well layer and the well layer; and
(C) a second GaN compound semiconductor layer 17 having p-type conductivity,
With
D ₁ The well layer density of the 1GaN based compound semiconductor layer side in the active layer 15, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, the active layer 15 so as to satisfy d _1> d ₂ The well layer in is arranged.

  The layer structure is conceptually shown in FIG. 11, and a schematic cross-sectional view is shown in FIG. 12A, and the GaN-based semiconductor constituting the light-emitting element 1 that emits light of different wavelengths based on different operating current densities. More specifically, the light emitting device 1A includes a buffer layer 11 (thickness 30 nm); an undoped GaN layer 12 (thickness 1 μm); a first GaN compound having an n-type conductivity type on a substrate 10 made of sapphire. Semiconductor layer 13 (thickness 3 μm); undoped GaN layer 14 (thickness 5 nm); active layer 15 (well layer and barrier) having a well layer and a barrier layer separating the well layer from the well layer Layer not shown); undoped GaN layer 16 (thickness 10 nm); second GaN-based compound semiconductor layer 17 (thickness 20 nm) having p-type conductivity; Mg-doped GaN layer (contact layer) 18 ( A thickness of 100 nm) has a structure and a structure that are sequentially stacked. In the drawings, the buffer layer 11, the undoped GaN layer 12, the undoped GaN layer 14, the undoped GaN layer 16, and the Mg-doped GaN layer 18 may be omitted. The undoped GaN layer 14 is provided to improve the crystallinity of the active layer 15 on which crystals are grown, and the undoped GaN layer 16 has a dopant (for example, Mg) in the second GaN compound semiconductor layer 17. It is provided to prevent diffusion into the active layer 15.

  Such a GaN-based semiconductor light-emitting element 1A is fixed to the submount 21, and the GaN-based semiconductor light-emitting element 1A is connected to the external electrode 23B via a wiring (not shown) provided on the submount 21 and a gold wire 23A. The external electrode 23B is electrically connected to the drive circuit 26. The submount 21 is attached to the reflector cup 24, and the reflector cup 24 is attached to the heat sink 25. Further, a plastic lens 22 is disposed above the GaN-based semiconductor light-emitting element 1A, and the light emitted from the GaN-based semiconductor light-emitting element 1A is interposed between the plastic lens 22 and the GaN-based semiconductor light-emitting element 1A. Transparent epoxy resin (refractive index: 1.5, for example), gel material [for example, trade name OCK-451 (refractive index: 1.51) of Nye, trade name OCK-433 (refractive index: 1.46) ], An oil compound material such as silicone rubber or silicone oil compound [for example, TSK5353 (refractive index: 1.45) of Toshiba Silicone Co., Ltd.] is filled with a light transmission medium layer (not shown). .

Then, d ₁ the well layer density of the 1GaN based compound semiconductor layer side in the active layer 15, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, activity so as to satisfy d _1> d ₂ A well layer in the layer 15 is arranged. Details of the multiple quantum well structure constituting the active layer 15 are shown in Table 1 below. In Table 1, the numbers in parentheses on the right side of the values of the well layer thickness and the barrier layer thickness are the first GaN-based compound semiconductor layer side interface in the active layer 15 (more specifically, Example 1). 2 shows the integrated thickness from the interface between the undoped GaN layer 14 and the active layer 15.

[Table 1]

In Example 1, the total thickness of the active layer 15 is t _0, and the first GaN-based compound semiconductor layer side interface in the active layer 15 (more specifically, in Example 1, the undoped GaN layer 14 the thickness from the interface) of the active layer _{15 (t 0/3) d} 1 of the well layer density in the active layer a first region AR ₁ up, the 2GaN based compound semiconductor layer side interface (more specifically, in example 1, when the thickness from the interface) between the undoped GaN layer 16 and the active layer 15 (2t _0/3) the well layer density in the active layer within the second region AR ₂ up to and d _2, The well layer in the active layer 15 is arranged so as to satisfy d ₁ > d ₂ .

In the first embodiment, there is one well layer (thickness t _IF = 3 nm, fifth well layer) straddling the active layer first region AR ₁ and the active layer second region AR ₂ . Accordingly, the number of well layers included in the active layer first region AR ₁ is WL ₁ , and the number of well layers included in the active layer second region AR ₂ is WL ₂ (where the total number of well layers WL = WL ₁ + WL ₂ ), The number of well layers included only in the active layer first region AR ₁ is WL ′ ₁ , and the number of well layers included only in the active layer second region AR ₂ is WL ′ ₂ . The thickness included in the active layer first region AR ₁ in the well layer straddling the region AR ₁ and the active layer second region AR ₂ is the thickness t _IF-1 and the thickness included in the active layer second region AR _2. When the thickness is t _IF-2 (t _IF = t _IF-1 + t _IF-2 ),
ΔWL ₁ = t _IF-1 / t _IF = 7/9
ΔWL ₂ = t _IF-2 / t _IF = 2/9
And
WL ₁ = WL ′ ₁ + ΔWL ₁ = 4 + 7/9
WL ₂ = WL ′ ₂ + ΔWL ₂ = 5 + 2/9
It is. Therefore, when the well layer density d ₁ and the well layer density d ₂ are obtained from the formulas (1-1) and (1-2), they are as follows.

[Example 1]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= {(4 + 7/9) / 10} / {(50 + 1/3) / 151}
= 1.43
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= {(5 + 2/9) / 10} / {(100 + 2/3) / 151}
= 0.78

  For comparison, a GaN-based semiconductor light-emitting element having an active layer shown in Table 1 as Comparative Example 1 was produced.

Note that the GaN-based semiconductor light-emitting elements of Example 1 and Comparative Example 1 have n-type conductivity based on the lithography process and the etching process for evaluation and for the sake of simplification of the manufacturing process. The first GaN-based compound semiconductor layer 13 is partially exposed to form a p-type electrode 19B made of Ag / Ni on the Mg-doped GaN layer 18, and the Ti-Al made of Ti / Al on the first GaN-based compound semiconductor layer 13. The n-type electrode 19A was formed, and the n-type electrode 19A and the p-type electrode 19B were probed with a probe, a drive current was supplied, and light emitted from the back surface of the substrate 10 was detected. This state is shown in the conceptual diagram of FIG. Further, a schematic view of the GaN-based semiconductor light emitting element 1A viewed from above is shown in FIG. 14A, and a schematic cross-sectional view taken along the arrow BB in FIG. ) Is shown in FIG. In the GaN-based semiconductor light emitting devices of Example 1 and Comparative Example 1, the active layer area (junction region area) was set to 6 × 10 ⁻⁴ cm ² . Accordingly, the operating current density of the GaN-based semiconductor light-emitting element is a value obtained by dividing the operating current value by 6 × 10 ⁻⁴ cm ² which is the active layer area (junction region area). For example, the operating current density when a driving current of 20 mA is passed through the GaN-based semiconductor light emitting device 1A shown in FIG. 14 is calculated as 33 A / cm ² . For example, even when the GaN-based semiconductor light emitting devices 1A as shown in FIG. 15 are connected in series, the operating current density is calculated to be 33 A / cm ² .

When the well layer density d ₁ and the well layer density d ₂ in Comparative Example 1 are obtained from the formulas (1-1) and (1-2), they are as follows.

[Comparative Example 1]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= {(3 + 1/3) / 10} / (49/147)
= 1.00
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= {(6 + 2/3) / 10} / (98/147)
= 1.00

  FIG. 16 shows the measurement result of the relationship between the operating current density of the GaN-based semiconductor light-emitting device and the light output. The light output of the GaN-based semiconductor light-emitting device 1A of Example 1 is the same as that of the conventional GaN-based semiconductor light-emitting device. It is the same level as a certain comparative example 1.

Furthermore, the relationship between the operating current density of the GaN-based semiconductor light-emitting element and the emission peak wavelength is shown in FIG. When the operating current density is increased from 0.1 A / cm ² to 300 A / cm ² , Δλ = −19 nm in Comparative Example 1, whereas Δλ = 19 nm in Example 1. A large emission wavelength shift of -31 nm is realized. That is, for example, when the operating current density is 0.1 A / cm ² , green light (emission wavelength 530 nm) is obtained, and when the operating current density is 10 A / cm ² , green light (emission wavelength 518 nm) is obtained. When the operating current density is 300 A / cm ² , blue-green (emission wavelength 499 nm) emission is obtained.

The control of the emission wavelength of such GaN based semiconductor light emitting device 1A may be employed a method of performing at peak current value I _1, I ₂ of the drive current. The light emission amount of the GaN-based semiconductor light emitting element 1A may be controlled by controlling the pulse width of the driving current, or may be controlled by controlling the pulse density of the driving current, or may be controlled by a combination thereof. Just do it. The same applies to the following embodiments.

Specifically, as shown in FIG. 12B, the peak current value of the drive current when obtaining a certain emission wavelength λ ₁ is I ₁ , the pulse width of the drive current is P ₁ , and the emission wavelength λ ₂ ( When the peak current value of the drive current when <λ ₁ ) is obtained is I ₂ (<I ₁ ), and the pulse width of the drive current is P ₂ ,
(1) By controlling the peak current values I ₁ and I ₂ of the drive current, the emission wavelength λ of the light emitted from the GaN-based semiconductor light-emitting element 1A can be controlled,
(2) By controlling the pulse width P ₁ and the pulse width P ₂ of the drive current (pulse width control of the drive current), it is possible to control the emission color as a whole of the light emitted from the GaN-based semiconductor light emitting device 1A. Yes, and
(3) (pulse width control of driving current) by controlling the length of one pulse period T _P of the GaN-based semiconductor light emitting device 1A (pulse width), the light emission amount of the light emitted from the GaN-based semiconductor light emitting device 1A ( Brightness and brightness) and / or
(3 ') (pulse density control of driving current) by controlling the number (pulse density) in one pulse period T _P in one operation during period T _OP of the operation of the GaN-based semiconductor light emitting device 1A, the GaN-based semiconductor light-emitting element The amount of light emitted from 1A (brightness, luminance) can be controlled.

  Even in the examples described later, the control of the emission wavelength of the GaN-based semiconductor light-emitting element 1A and the control of the light emission amount of the GaN-based semiconductor light-emitting element 1A may be performed by the same method.

Note that the total thickness of the active layer 15 is t _0, and the thickness (t ₀ ) from the first GaN-based compound semiconductor layer side interface (more specifically, the interface between the undoped GaN layer 14 and the active layer 15) in the active layer 15. / 2), the density of the well layer in the active layer first region AR ₁ is d ₁ , the thickness from the second GaN compound semiconductor layer side interface (more specifically, the interface between the undoped GaN layer 16 and the active layer 15). is (t _0/2) of the well layer density in the active layer within the second region AR ₂ up when the d _2, when the well layer in the active layer 15 so as to satisfy d _1> d ₂ is arranged In this case, the well layer density d ₁ and the well layer density d ₂ are obtained from the equations (1-1) and (1-2) as follows.

[Equivalent to Example 1]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= (6/10) / {(75 + 1/2) / 151}
= 1.20
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= (4/10) / {(75 + 1/2) / 151}
= 0.78

[Comparative example 1 equivalent]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= (5/10) / {(73 + 1/2) / 147}
= 1.00
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= (5/10) / {(73 + 1/2) / 147}
= 1.00

Further, the total thickness of the active layer 15 is t _0, and the thickness (2t ₀ ) from the first GaN-based compound semiconductor layer side interface (more specifically, the interface between the undoped GaN layer 14 and the active layer 15) in the active layer 15. / 3) the well layer density in the active layer first region AR ₁ is d ₁ , the thickness from the second GaN compound semiconductor layer side interface (more specifically, the interface between the undoped GaN layer 16 and the active layer 15). is (t _0/3) the well layer density in the active layer within the second region AR ₂ up when the d _2, when the well layer in the active layer 15 so as to satisfy d _1> d ₂ is arranged In this case, the well layer density d ₁ and the well layer density d ₂ are obtained from the equations (1-1) and (1-2) as follows.

[Equivalent to Example 1]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= (7/10) / {(100 + 2/3) / 151}
= 1.05
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= (3/10) / {(50 + 1/3) / 151}
= 0.90

[Comparative example 1 equivalent]
d ₁ = (WL ₁ / WL) / (t ₁ / t ₀ )
= {(6 + 2/3) / 10} / (98/147)
= 1.00
d ₂ = (WL ₂ / WL) / (t ₂ / t ₀ )
= {(3 + 1/3) / 10} / (49/147)
= 1.00

As described above, in any case, in the case corresponding to Example 1, the well layer in the active layer 15 is arranged so as to satisfy d ₁ > d ₂ .

  As shown in FIG. 12A, the drive circuit 26 according to the first embodiment includes a control unit 27, a drive current source 28 that is a drive current supply source, and a pulse generation circuit 29 that generates a predetermined pulse signal. The driver 30 is provided. Here, the drive current source 28, the pulse generation circuit 29, and the driver 30 correspond to pulse drive current supply means for supplying a pulse drive current to the GaN-based semiconductor light emitting device 1A. The control unit 27 corresponds to pulse driving current setting means for setting the pulse width and pulse density of the pulse driving current.

In the drive circuit 26, the peak current values I ₁ and I ₂ of the drive current are output from the drive current source 28 under the control of the control unit 27. In addition, under control of the control unit 27 controls the length of one pulse period T _P of the GaN-based semiconductor light emitting device 1A (pulse width), yet that one operation period T _OP of the operation of the GaN-based semiconductor light emitting device 1A to control the number of one pulse period T _P (pulse density) in, and outputs a pulse signal from the pulse generating circuit 29. In the driver 30 that has received these drive current and pulse signal, the drive current sent from the drive current source 28 is subjected to pulse modulation based on the pulse signal sent from the pulse generation circuit 29, and This pulse driving current is supplied to the GaN-based semiconductor light emitting device 1A. As a result, the emission wavelength of the GaN-based semiconductor light-emitting element 1A is controlled, and the light emission amount of the GaN-based semiconductor light-emitting element 1A is controlled.

  The outline of the method for manufacturing the GaN-based semiconductor light emitting device 1A of Example 1 will be described below.

[Step-100]
First, sapphire having a C-plane as a main surface is used as the substrate 10, and after performing substrate cleaning for 10 minutes at a substrate temperature of 1050 ° C. in a carrier gas composed of hydrogen, the substrate temperature is lowered to 500 ° C. Then, based on the MOCVD method, while supplying ammonia gas, which is a nitrogen source, trimethyl gallium (TMG) gas, which is a gallium source, is supplied, and a buffer layer 11 made of low-temperature GaN having a thickness of 30 nm is formed on the substrate 10. After the crystal is grown above, the supply of TMG gas is interrupted.

[Step-110]
Next, after raising the substrate temperature to 1020 ° C., the supply of TMG gas is started again to grow an undoped GaN layer 12 having a thickness of 1 μm on the buffer layer 11. By supplying a certain monosilane (SiH ₄ ) gas, the first GaN-based compound semiconductor layer 13 made of Si-doped GaN (GaN: Si) and having an n-type conductivity and having a thickness of 3 μm is formed into undoped GaN. Crystals are grown on the layer 12. The doping concentration is about 5 × 10 ¹⁸ / cm ³ .

[Step-120]
Thereafter, the supply of TMG gas and SiH ₄ gas is temporarily interrupted, the carrier gas is switched from hydrogen gas to nitrogen gas, and the substrate temperature is lowered to 750 ° C. Then, triethylgallium (TEG) gas is used as a Ga raw material, and trimethylindium (TMI) gas is used as an In raw material, and these gases are supplied by switching valves. The GaN layer 14 is crystal-grown, and subsequently, an active layer 15 having a multiple quantum well structure composed of a well layer made of InGaN and a barrier layer made of GaN is formed. The In composition ratio in the well layer is, for example, 0.23, which corresponds to the emission wavelength λ515 nm. The In composition ratio in the well layer may be determined based on a desired emission wavelength. The details of the multiple quantum well structure are as shown in Table 1, for example.

[Step-130]
After completing the formation of the multi-quantum well structure, the substrate temperature is raised to 800 ° C. while growing an undoped 10 nm GaN layer 16, and trimethylaluminum (TMA) gas is used as the Al source, and biscyclopenta is used as the Mg source. By starting supply of dienylmagnesium (Biscyclopentadienyl Magnesium, Cp ₂ Mg) gas, a 20 nm-thick 20 μm-thick p-type conductive layer composed of AlGaN (AlGaN: Mg) with an Mg-doped Al composition ratio of 0.20 The 2GaN compound semiconductor layer 17 is crystal-grown. The doping concentration is about 5 × 10 ¹⁹ / cm ³ .

[Step-140]
After that, with the interruption of the supply of TEG gas, TMA gas, and Cp ₂ Mg gas, the carrier gas is switched from nitrogen to hydrogen, the substrate temperature is increased to 850 ° C., and the supply of TMG gas and Cp ₂ Mg gas is started. Then, an Mg-doped GaN layer (GaN: Mg) 18 having a thickness of 100 nm is grown on the second GaN-based compound semiconductor layer 17. The doping concentration is about 5 × 10 ¹⁹ / cm ³ . Thereafter, the substrate temperature is lowered at the same time as the supply of TMG gas and Cp ₂ Mg gas is stopped, the supply of ammonia gas is stopped at the substrate temperature of 600 ° C., and the substrate temperature is lowered to room temperature to complete the crystal growth.

Here, regarding the substrate temperature T _MAX after the growth of the active layer 15, when the emission wavelength is λ nm, T _MAX <1350-0.75λ (° C.), preferably T _MAX <1250-0.75λ ( ° C) is satisfied. By adopting the substrate temperature T _MAX after the growth of the active layer 15 as described above, as described in JP-A-2002-319702, thermal degradation of the active layer 15 can be suppressed.

  After crystal growth is thus completed, the substrate is annealed at 800 ° C. for 10 minutes in a nitrogen gas atmosphere to activate p-type impurities (p-type dopants). Then, in the same way as the normal LED wafer process and chip forming process, the chip is formed by dicing through the photolithography process, etching process, p-type electrode and metal n-type electrode forming process, and resin mold. By packaging, various light emitting diodes such as a shell type and a surface mount type can be manufactured.

  The second embodiment is a modification of the first embodiment. In the GaN-based semiconductor light emitting device 1A according to the second embodiment, between the first GaN-based compound semiconductor layer 13 and the active layer 15 (more specifically, in the second embodiment, the first GaN-based compound semiconductor layer). 13 and the undoped GaN layer 14), an underlayer containing In atoms is formed. Between the active layer 15 and the second GaN-based compound semiconductor layer 17 (more specifically, in Example 2) In this case, a superlattice structure layer containing a p-type dopant is formed between the undoped GaN layer 16 and the second GaN-based compound semiconductor layer 17. With such a configuration, it is possible to achieve a more stable operation of the GaN-based semiconductor light-emitting element 1A at a high operating current density while further improving the light emission efficiency and further reducing the operating voltage.

Here, the underlayer is composed of a 150 nm thick Si-doped InGaN layer having an In composition ratio of 0.03. The doping concentration is 5 × 10 ¹⁸ / cm ³ . On the other hand, the superlattice structure layer has a superlattice structure in which an AlGaN layer (Mg doping) having a thickness of 2.4 nm and a GaN layer (Mg doping) having a thickness of 1.6 nm are stacked in five periods. The Al composition ratio in the AlGaN layer is 0.15. The concentration of the p-type dopant contained in the superlattice structure layer is 5 × 10 ¹⁹ / cm ³ .

  Except for the above points, the GaN-based semiconductor light-emitting element 1A in Example 2 has the same configuration and structure as the GaN-based semiconductor light-emitting element 1A in Example 1, and thus detailed description thereof is omitted.

The third embodiment is also a modification of the first embodiment. Specifically, the image display apparatus according to the third embodiment relates to the image display apparatus according to the mode 1B, and as illustrated in a conceptual diagram in FIG.
(Α) A first light-emitting element 101B that is composed of a GaN-based semiconductor light-emitting element and controls the passage / non-passage of the emitted light emitted from the first light-emitting element 101B that emits blue light and the first light-emitting element 101B that emits blue light. From a light passage control device [a kind of light valve, which is composed of, for example, a liquid crystal display device 58B including a high-temperature polysilicon type thin film transistor and a digital micromirror device (DMD), and the same applies to the following description) A first image display device comprising:
(Β) a second light-emitting element 101G that is composed of a GaN-based semiconductor light-emitting element and controls the passage / non-passage of the emitted light emitted from the second light-emitting element 101G that emits green light and the second light-emitting element 101G that emits green light. A second image display device comprising a light passage control device (for example, a liquid crystal display device 58G), and
(Γ) For example, an AlGaInP-based semiconductor light-emitting device or a GaN-based semiconductor light-emitting device is used, and the passage / non-transmission of light emitted from the third light-emitting device 101R that emits red light and the third light-emitting device 101R that emits red light. A third image display device comprising a third light passage control device (for example, a liquid crystal display device 58R) for controlling the passage, and
(Δ) means (dichroic prism 57) for collecting the light that has passed through the first light passage control device 58B, the second light passage control device 58G, and the third light passage control device 58R into one optical path;
With
This is a color display image display device (direct view type or projection type) that displays an image by controlling passage / non-passage of the emitted light emitted from these light emitting elements by the light passage control devices 58B, 58G, 58R.

  Note that the number of the first light emitting element 101B, the second light emitting element 101G, and the third light emitting element 101R may be determined based on specifications required for the image display apparatus, and may be one or more. In the example, each is one. Further, means for guiding the light emitted from the first light emitting element 101B, the second light emitting element 101G, and the third light emitting element 101R to the light passage control devices 58B, 58G, 58R (light guide members 59B, 59G, Examples of 59R) include a light guide member, a microlens array, a mirror, a reflector, and a condenser lens.

  Here, as in Example 1, the first light emitting element 101B that emits blue light and the third light emitting element 101R that emits red light each include a GaN-based semiconductor light emitting element 1A that emits one color and emits green light. The second light-emitting element 101G can be configured to emit two colors (total four-color configuration). The first light-emitting element 101B that emits blue light and the third light-emitting element 101R that emits red light are: Each of the second light emitting elements 101G, which emits one color and is composed of the green light emitting GaN-based semiconductor light emitting element 1A, can be configured to emit three colors (a total of five colors), or red. The third light-emitting element 101R that emits light emits one color, and the second light-emitting element includes the first light-emitting element 101B including the blue-emitting GaN-based semiconductor light-emitting element 1A and the green light-emitting GaN-based semiconductor light-emitting element 1A. 101G can be configured to emit two colors (a total of five colors), or the third light emitting element 101R that emits red light emits one color and emits blue light. The first light-emitting element 101B made of the material emits two colors, and the second light-emitting element 101G made of the green light-emitting GaN-based semiconductor light-emitting element 1A emits three colors (a structure that emits six colors in total). You can also. The GaN-based semiconductor light-emitting element 1A that emits two or more colors may have the same configuration and structure as the GaN-based semiconductor light-emitting element 1A described in the first or second embodiment.

In addition, as shown in a conceptual diagram in FIG. 19, an image display device according to the 1D mode can be provided. Specifically, this image display device is
(Α) a first image display device including a first light emitting element 101B that emits blue light;
(Β) a second image display device including a second light emitting element 101G that emits green light, and
(Γ) a third image display device including a third light emitting element 101R that emits red, and
(Δ) means (dichroic prism 57) for collecting the light emitted from the first image display device, the second image display device, and the third image display device into one optical path;
(Ε) Means for grouping into one optical path (light passage control device (liquid crystal display device 58) for controlling passage / non-passage of light emitted from the dichroic prism 57,
With
A field sequential type color display image display device (direct view type or direct view type) that displays an image by controlling the passage / non-passage of the light emitted from the light emitting elements 101B, 101G, 101R by the light passage control device 58. Projection type).

  In the image display device according to the first D aspect, the light emitted from the light emitting elements 101R, 101G, and 101B enters the dichroic prism 57, and the optical paths of these lights are combined into one optical path. These light beams emitted from the dichroic prism 57 are controlled to pass / non-pass by the light passage control device 58. In the direct view type image display device, the light is directly seen or in the projection type image display device. Is projected onto the screen via the projection lens 56.

The fourth embodiment is also a modification of the first embodiment. Specifically, the image display apparatus of Example 4 relates to the image display apparatus according to the first C aspect, and as illustrated in a conceptual diagram in FIG.
(Α) The first light emitting element panel 50B in which the first light emitting elements 1B emitting blue light are arranged in a two-dimensional matrix, and the passage / non-passage of the emitted light emitted from the first light emitting element panel 50B are controlled. A first image display device comprising a blue light passage control device (liquid crystal display device 58B) for
(Β) Controls the second light emitting element panel 50G in which the second light emitting elements 1G emitting green light are arranged in a two-dimensional matrix, and the passage / non-passage of the light emitted from the second light emitting element panel 50G. A second image display device comprising a green light passage control device (liquid crystal display device 58G) for
(Γ) The third light emitting element panel 50R in which the third light emitting elements 1R emitting red light are arranged in a two-dimensional matrix, and the passage / non-passage of the light emitted from the third light emitting element panel 50R are controlled. A third image display device comprising a red light passage control device (liquid crystal display device 58R), and
(Δ) includes means (dichroic prism 57) for collecting the light that has passed through the blue light passage control device 58B, the green light passage control device 58G, and the red light passage control device 58R into one optical path;
The light passing control devices 58B, 58G, and 58R control the passage / non-passing of the emitted light emitted from the first light emitting element panel 50B, the second light emitting element panel 50G, and the third light emitting element panel 50R, thereby displaying an image. This is a color display image display device (direct view type or projection type).

  In the image display device according to the first C mode, the light emitted from the light emitting element panels 50R, 50G, and 50B is controlled to pass / non-pass by the light passage control devices 58R, 58G, and 58B. The light path is incident on the prism 57, and the optical paths of these lights are combined into a single optical path. In a direct-view image display apparatus, the light path is viewed directly, or in a projection-type image display apparatus, a projection lens 56 is provided. And projected on the screen. The configuration and structure of the light emitting element panels 50R, 50G, and 50B can be the same as the configuration and structure of the light emitting element panel 50 described with reference to FIG.

  Here, as in Example 1, the first light emitting element 1B that emits blue light and the third light emitting element 1R that emits red light each include a GaN-based semiconductor light emitting element 1A that emits one color and emits green light. The second light-emitting element 1G can be configured to emit two colors (total four-color configuration). The first light-emitting element 1B that emits blue light and the third light-emitting element 1R that emits red light are: Each of the second light emitting elements 1G, which emits one color and is composed of a green light emitting GaN-based semiconductor light emitting element 1A, can be configured to emit three colors (a total of five colors), or red. The third light-emitting element 1R that emits light emits one color, and the first light-emitting element 1B composed of the blue-emitting GaN-based semiconductor light-emitting element 1A and the second light-emitting element 1G composed of the green-emitting GaN-based semiconductor light-emitting element 1A have two colors. Configuration that emits light (total The third light emitting element 1R that emits red light emits one color, and the first light emitting element 1B composed of the blue light emitting GaN-based semiconductor light emitting element 1A emits two colors. The second light-emitting element 1G including the GaN-based semiconductor light-emitting element 1A that emits light and emits green light can also be configured to emit three colors (a total of six colors). The GaN-based semiconductor light-emitting element 1A that emits two or more colors may have the same configuration and structure as the GaN-based semiconductor light-emitting element 1A described in the first or second embodiment.

In addition, as shown in a conceptual diagram in FIG. 21, the image display device according to the 1E mode may be used. Specifically, this image display device is
(Α) a first image display device including a first light emitting element panel 50B in which first light emitting elements 1B emitting blue light are arranged in a two-dimensional matrix;
(Β) a second image display device including a second light emitting element panel 50G in which the second light emitting elements 1G emitting green light are arranged in a two-dimensional matrix, and
(Γ) a third image display device including a third light emitting element panel 50R in which the third light emitting elements 1R emitting red light are arranged in a two-dimensional matrix, and
(Δ) emitted from each of the first image display device (first light emitting element panel 50B), the second image display device (second light emitting element panel 50G), and the third image display device (third light emitting element panel 50R). Means (dichroic prism 57) for collecting light into one optical path,
(Ε) a light passage control device (liquid crystal display device 58) for controlling passage / non-passage of light emitted from a means (dichroic prism 57) for gathering in one optical path;
With
A field-sequential color display image display device (direct view type or projection type) that displays an image by controlling passage / non-passage of light emitted from these light emitting element panels by a light passage control device 58. is there.

  In the image display device according to the first aspect, the light emitted from the light emitting element panels 50R, 50G, and 50B is incident on the dichroic prism 57, and the optical paths of these lights are combined into one optical path. These light beams emitted from the dichroic prism 57 are controlled to pass / non-pass by the light passage control device 58. In the direct view type image display device, the light is directly seen or is not suitable for the projection type image display device. Then, it is projected onto the screen via the projection lens 56. The configuration and structure of the light emitting element panels 50R, 50G, and 50B can be the same as the configuration and structure of the light emitting element panel 50 described with reference to FIG.

  Example 5 relates to an image display device according to a second aspect of the present invention. The image display device according to the fifth embodiment includes a first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light. This is an image display device in which the element units UN are arranged in a two-dimensional matrix. At least one of the first light emitting element, the second light emitting element, and the third light emitting element is composed of a GaN-based semiconductor light-emitting element, and the GaN-based semiconductor light-emitting element has different operating current densities. Based on this, light of different wavelengths is emitted.

  In such an image display device, the GaN-based semiconductor light-emitting element that emits light of different wavelengths based on different operating current densities is the same as the GaN-based semiconductor light-emitting element 1A described in the first or second embodiment. The other light-emitting elements may be composed of GaN-based semiconductor light-emitting elements, or, for example, red light-emitting elements may be composed of AlInGaP-based compound semiconductor light-emitting diodes.

  Even in the image display apparatus according to the fifth embodiment, it is possible to display four or more colors just by preparing three types of light emitting elements for displaying three primary colors (RGB) as in the conventional case. For example, when priority is given to brightness or when displaying a conventional video source, one or more colors can be displayed in addition to the three primary colors in order to expand the color reproduction range. Both can be easily switched by a drive current waveform or the like. In addition, the GaN-based semiconductor light-emitting element to be used is not wasted in any display, which helps to reduce the number of parts and the cost.

  Here, examples of the image display apparatus according to the fifth embodiment include an image display apparatus having a configuration and a structure described below. The number of light emitting element units UN may be determined based on specifications required for the image display device.

[1] Image display device according to aspect 2A and image display device according to aspect 2B By controlling the light emitting / non-light emitting states of the first light emitting element, the second light emitting element, and the third light emitting element, Passive matrix type or active matrix type direct-view type color display image display device that directly displays the light emission state of each light emitting element, and the first light emitting element, the second light emitting element, and the first light emitting element A passive matrix type or active matrix type projection type color display image display device that controls the light emission / non-light emission state of each of the three light emitting elements and displays the image by projecting it onto a screen.

  For example, FIG. 22 shows a circuit diagram including a light-emitting element panel constituting such an active matrix type direct-view type color display image display device. Each light-emitting element 1 (in FIG. 22, light emission that emits red light) is shown. The element is indicated by “R”, the GaN-based semiconductor light-emitting element emitting green light is indicated by “G”, and the GaN-based semiconductor light-emitting element emitting blue light is indicated by “B”) (p-type electrode or n Type electrode) is connected to a driver 45, and the driver 45 is connected to a column driver 43 and a row driver 44. The other electrode (n-type electrode or p-type electrode) of each light-emitting element 1 is connected to a ground line. The light emitting / non-light emitting state of each light emitting element 1 is controlled by, for example, selection of the driver 45 by the row driver 44, and a luminance signal for driving each light emitting element 1 is supplied from the column driver 43 to the driver 45. The A predetermined voltage is separately supplied to each driver 45 from a power source (not shown), and the driver 45 supplies a drive current (based on PDM control or PWM control) corresponding to the luminance signal to the light emitting element 1. One of the functions of the column driver 43 is the same as the function of the drive circuit 26 in the first embodiment. The light emitting element R that emits red light, the GaN-based semiconductor light emitting element G that emits green light, and the GaN-based semiconductor light emitting element B that emits blue light are selected by the driver 45, and the light emitting element R that emits red light, green The light emission / non-light emission states of the GaN-based semiconductor light-emitting element G that emits blue light and the GaN-based semiconductor light-emitting element B that emits blue light may be time-division controlled, or may be simultaneously emitted. Since the selection and driving of each light emitting element 1 can be a well-known method, detailed description is omitted. In the direct-view image display device, it is directly viewed, or in the projection-type image display device, it is projected onto the screen via a projection lens.

[2] Image display device according to 2C mode A light passage control device (for example, a liquid crystal display device) for controlling passage / non-passage of light emitted from the light emitting element units UN arranged in a two-dimensional matrix A light-emitting / non-light-emitting state of each of the first light-emitting element, the second light-emitting element, and the third light-emitting element in the light-emitting element unit UN is controlled in a time-sharing manner. A field-sequential color display direct-view or projection-type image display device that displays an image by controlling passage / non-passage of light emitted from the second light-emitting element and the third light-emitting element.

  The circuit diagram including the light emitting element panel constituting such a passive matrix type image display device is the same as that shown in FIG. 2A, and the light emitting element panel constituting the active matrix type image display device is the same as that shown in FIG. The circuit diagram to be included is the same as that shown in FIG. FIG. 23 shows a conceptual diagram of the light emitting element panel 50 and the like in which the light emitting elements 1 are arranged in a two-dimensional matrix. Light emitted from the light emitting element panel 50 is projected onto the screen via the projection lens 56. Or alternatively, it is viewed directly. The configuration and structure of the light-emitting element panel 50 can be the same as the configuration and structure of the light-emitting element panel 50 described with reference to FIG.

  Here, as in Example 1, the first light-emitting element B that emits blue light and the third light-emitting element R that emits red light each include a GaN-based semiconductor light-emitting element 1A that emits one color and emits green light. The second light-emitting element G can be configured to emit two colors (total four-color configuration). The first light-emitting element B that emits blue light and the third light-emitting element R that emits red light are: Each of the second light-emitting elements G that emit light of one color and that is composed of the GaN-based semiconductor light-emitting element 1A that emits green light can also be configured to emit three colors (total of five colors to emit light). The third light-emitting element R that emits light emits one color, and the first light-emitting element B that includes the blue-emitting GaN-based semiconductor light-emitting element 1A and the second light-emitting element G that includes the green-emitting GaN-based semiconductor light-emitting element 1A have two colors. (A total of five colors) The third light emitting element R that emits red light emits one color, and the first light emitting element B composed of the blue light emitting GaN-based semiconductor light emitting element 1A emits two colors and emits green light. The second light-emitting element G composed of the GaN-based semiconductor light-emitting element 1A can be configured to emit three colors (a total of six colors). The GaN-based semiconductor light-emitting element 1A that emits two or more colors may have the same configuration and structure as the GaN-based semiconductor light-emitting element 1A described in the first or second embodiment.

  Example 6 relates to a planar light source device and a liquid crystal display device assembly (specifically, a color liquid crystal display device assembly) according to the present invention. The planar light source device of Example 6 is a planar light source device that irradiates a transmissive or transflective color liquid crystal display device from the back side. Further, the color liquid crystal display device assembly of Example 6 is a color liquid crystal display device assembly including a transmissive or transflective color liquid crystal display device and a planar light source device that irradiates the color liquid crystal display device from the back side. It is a solid.

  FIG. 24A schematically shows the arrangement and arrangement of the light emitting elements in the planar light source device of Example 6, and a schematic partial sectional view of the planar light source device and the color liquid crystal display device assembly. A schematic partial sectional view of the color liquid crystal display device shown in FIG.

  The planar light source device in Example 6 includes a first light emitting element 1B that emits blue light, a second light emitting element 1G that emits green light, and a third light emitting element 1R that emits red light. 1B, at least one of the second light emitting element 1G and the third light emitting element 1R is composed of a GaN-based semiconductor light-emitting element 1A, which is based on different operating current densities. Emits light of different wavelengths.

  Here, as in Example 1, the first light emitting element 1B that emits blue light and the third light emitting element 1R that emits red light each include a GaN-based semiconductor light emitting element 1A that emits one color and emits green light. The second light-emitting element 1G can be configured to emit two colors (total four-color configuration). The first light-emitting element 1B that emits blue light and the third light-emitting element 1R that emits red light are: Each of the second light emitting elements 1G, which emits one color and is composed of a green light emitting GaN-based semiconductor light emitting element 1A, can be configured to emit three colors (a total of five colors), or red. The third light-emitting element 1R that emits light emits one color, and the first light-emitting element 1B composed of the blue-emitting GaN-based semiconductor light-emitting element 1A and the second light-emitting element 1G composed of the green-emitting GaN-based semiconductor light-emitting element 1A have two colors. Configuration that emits light (total The third light emitting element 1R that emits red light emits one color, and the first light emitting element 1B composed of the blue light emitting GaN-based semiconductor light emitting element 1A emits two colors. The second light-emitting element 1G including the GaN-based semiconductor light-emitting element 1A that emits light and emits green light can also be configured to emit three colors (a total of six colors). The GaN-based semiconductor light-emitting element 1A that emits two or more colors may have the same configuration and structure as the GaN-based semiconductor light-emitting element 1A described in the first or second embodiment.

More specifically, the color liquid crystal display device assembly 200 according to the sixth embodiment includes:
(A) a front panel 220 having a transparent first electrode 224;
(B) a rear panel 230 having a transparent second electrode 234, and
(C) a liquid crystal material 227 disposed between the front panel 220 and the rear panel 230;
A transmissive color liquid crystal display device 210 comprising:
(D) a planar light source device (direct backlight) 240 having light emitting elements 1R, 1G, and 1B as light sources;
It has. Here, the planar light source device (direct-type backlight) 240 is disposed to face (face to face) the rear panel 230 and irradiates the color liquid crystal display device 210 from the rear panel side.

  The direct type planar light source device 240 includes a housing 241 including an outer frame 243 and an inner frame 244. The end of the transmissive color liquid crystal display device 210 is held by the outer frame 243 and the inner frame 244 so as to be sandwiched between the spacers 245A and 245B. Further, a guide member 246 is disposed between the outer frame 243 and the inner frame 244 so that the color liquid crystal display device 210 sandwiched between the outer frame 243 and the inner frame 244 does not shift. A diffusion plate 251 is attached to the inner frame 244 via a spacer 245 </ b> C and a bracket member 247 inside and above the housing 241. On the diffusion plate 251, an optical function sheet group such as a diffusion sheet 252, a prism sheet 253, and a polarization conversion sheet 254 is laminated.

  A reflection sheet 255 is provided inside and below the housing 241. Here, the reflection sheet 255 is disposed so that the reflection surface thereof faces the diffusion plate 251, and is attached to the bottom surface 242 </ b> A of the housing 241 via an attachment member (not shown). The reflection sheet 255 can be composed of, for example, a silver-enhanced reflection film having a structure in which a silver reflection film, a low refractive index film, and a high refractive index film are sequentially laminated on a sheet base material. The reflective sheet 255 includes a plurality of AlGaInP semiconductor light emitting devices 1R that emit red light, a plurality of GaN semiconductor light emitting devices 1G that emit green light, a plurality of GaN semiconductor light emitting devices 1B that emit blue light, The light reflected by the side surface 242B of the housing 241 is reflected. Thus, red, green, and blue emitted from the plurality of semiconductor light emitting elements 1R, 1G, and 1B are mixed, and white light with high color purity can be obtained as illumination light. The illumination light passes through the optical function sheet group such as the diffusion plate 251, the diffusion sheet 252, the prism sheet 253, and the polarization conversion sheet 254, and irradiates the color liquid crystal display device 210 from the back side.

  The arrangement of the light emitting elements is, for example, from the first light emitting element 1B made of a blue light emitting GaN semiconductor light emitting element, the third light emitting element 1R made of a red light emitting AlGaInP semiconductor light emitting element, and the green light emitting GaN semiconductor light emitting element. A plurality of light emitting element arrays each including the second light emitting elements 1G formed in the horizontal direction are connected to form a light emitting element array, and a plurality of the light emitting element arrays can be arranged in the vertical direction. The number of light emitting elements constituting the light emitting element array is, for example, (one blue light emitting first light emitting element, two green light emitting second light emitting elements, and two red light emitting third light emitting elements). The third light emitting element emitting red light, the second light emitting element emitting green light, the first light emitting element emitting blue light, the second light emitting element emitting green light, and the third light emitting element emitting red light are arranged in this order.

  As shown in FIG. 25, the front panel 220 constituting the color liquid crystal display device 210 includes, for example, a first substrate 221 made of a glass substrate and a polarizing film 226 provided on the outer surface of the first substrate 221. It is configured. A color filter 222 covered with an overcoat layer 223 made of acrylic resin or epoxy resin is provided on the inner surface of the first substrate 221, and a transparent first electrode (also called a common electrode) is provided on the overcoat layer 223. (For example, made of ITO) 224 is formed, and an alignment film 225 is formed on the transparent first electrode 224. On the other hand, the rear panel 230 more specifically includes, for example, a second substrate 231 made of a glass substrate, and switching elements (specifically, thin film transistors and TFTs) formed on the inner surface of the second substrate 231. 232, a transparent second electrode (also referred to as a pixel electrode, made of, for example, ITO) 234 whose conduction / non-conduction is controlled by the switching element 232, and a polarizing film 236 provided on the outer surface of the second substrate 231, It is composed of An alignment film 235 is formed on the entire surface including the transparent second electrode 234. The front panel 220 and the rear panel 230 are joined to each other at the outer peripheral portion via a sealing material (not shown). Note that the switching element 232 is not limited to a TFT, and may be composed of, for example, an MIM element. Reference numeral 237 in the drawing denotes an insulating layer provided between the switching element 232 and the switching element 232.

  Various members and liquid crystal materials constituting these transmissive color liquid crystal display devices can be composed of well-known members and materials, and thus detailed description thereof is omitted.

  Each of the blue light emitting first light emitting element 1B, the green light emitting second light emitting element 1G, and the red light emitting third light emitting element 1R has the structure shown in FIG. 12A and is connected to the drive circuit 26. ing. And it drives by the method similar to having demonstrated in Example 1. FIG.

  When using multiple colors in this way, the conventional technology requires light-emitting diodes corresponding to the respective colors, but in Example 6, there are three types of light-emitting diodes, that is, a normal red color. Only a light emitting diode that emits light, a light emitting diode that emits green light, and a light emitting diode that emits blue light may be prepared. In addition, when light emitting diodes for each color are individually prepared for multiple colors, they are wasted because they are not used in the case of normal three primary colors display. Since it is used as a primary color light source, it is not wasted. In other words, by preparing three types of light emitting diodes for displaying three primary colors, when priority is given to brightness or when displaying a conventional video source, three primary colors and four or more colors should be used to expand the color reproduction range. Both can be displayed and can be easily switched by the drive current waveform. Further, the light emitting diode to be used is not wasted in any display, which helps to reduce the number of parts and the cost. As the red light emitting semiconductor light emitting element, in addition to the AlGaInP based semiconductor light emitting element, a GaN based semiconductor light emitting element can also be used. The same applies to the seventh embodiment.

  In addition, by dividing the planar light source device into a plurality of regions and dynamically controlling each region independently, it is possible to widen the dynamic range related to the luminance of the color liquid crystal display device. That is, the planar light source device is divided into a plurality of regions for each image display frame, and the brightness of the planar light source device is changed according to the image signal for each region (for example, an image region corresponding to each region). The brightness of the corresponding area of the planar light source device is proportional to the maximum brightness of the light source), so that the corresponding area of the planar light source device is brightened in the bright area of the image and the dark area of the image is The contrast ratio of the color liquid crystal display device can be greatly improved by darkening the corresponding region of the planar light source device. Furthermore, the average power consumption can be reduced. In this technique, it is important to reduce color unevenness between areas of the planar light source device. The GaN-based semiconductor light-emitting element is likely to cause variations in emission color during manufacture, but the GaN-based semiconductor light-emitting element 1A used in Example 6 is the GaN-based semiconductor light-emitting element 1A described in Example 1 or Example 2. Since the emission wavelength can be changed greatly only by changing the peak current value, the emission current variation is corrected by adjusting the peak current value for each area of the planar light source device, and the pulse width and / or drive current is corrected. The luminance can be adjusted by the pulse density. Thereby, a planar light source device with little variation in emission color for each region can be achieved.

  The seventh embodiment is a modification of the sixth embodiment. In Example 6, the planar light source device was a direct type. On the other hand, in Example 7, the planar light source device is an edge light type. A conceptual diagram of a color liquid crystal display device assembly of Example 7 is shown in FIG. A schematic partial cross-sectional view of the color liquid crystal display device in Example 7 is the same as the schematic partial cross-sectional view shown in FIG.

The color liquid crystal display device assembly 200A of Example 7 is
(A) a front panel 220 having a transparent first electrode 224;
(B) a rear panel 230 having a transparent second electrode 234, and
(C) a liquid crystal material 227 disposed between the front panel 220 and the rear panel 230;
A transmissive color liquid crystal display device 210 comprising:
(D) A planar light source device (edge light type backlight) 250 that includes a light guide plate 270 and a light source 260 and irradiates the color liquid crystal display device 210 from the rear panel side.
It has. Here, the light guide plate 270 is disposed so as to face (face to face) the rear panel 230.

  The light source 260 is, for example, a third light emitting element composed of a red light emitting AlGaInP semiconductor light emitting element, a second light emitting element composed of a green light emitting GaN semiconductor light emitting element, and a first light emitting element composed of a blue light emitting GaN semiconductor light emitting element. It is comprised from the light emitting element. Note that these light emitting elements are not specifically shown. The second light emitting element emitting green light and the first light emitting element emitting blue light can be the same as the GaN-based semiconductor light emitting element 1A described in Example 1 or Example 2. Further, the configurations and structures of the front panel 220 and the rear panel 230 constituting the color liquid crystal display device 210 are the same as those of the front panel 220 and the rear panel 230 of the sixth embodiment described with reference to FIG. Since it can be set as a structure, detailed description is abbreviate | omitted.

  For example, the light guide plate 270 made of polycarbonate resin has a first surface (bottom surface) 271, a second surface (top surface) 273 facing the first surface 271, a first side surface 274, a second side surface 275, and a first side surface 274. A third side surface 276 that faces the second side surface 274 and a fourth side surface that faces the second side surface 274. A more specific shape of the light guide plate 270 is a wedge-shaped truncated quadrangular pyramid as a whole, and two opposing side surfaces of the truncated quadrangular pyramid correspond to the first surface 271 and the second surface 273, and the truncated surface. The bottom surface of the quadrangular pyramid corresponds to the first side surface 274. An uneven portion 272 is provided on the surface portion of the first surface 271. The cross-sectional shape of the continuous convex and concave portions when the light guide plate 270 is cut in a virtual plane perpendicular to the first surface 271 in the light incident direction to the light guide plate 270 is a triangle. That is, the concavo-convex portion 272 provided on the surface portion of the first surface 271 has a prism shape. The second surface 273 of the light guide plate 270 may be smooth (that is, may be a mirror surface) or may be provided with a blast texture having a diffusion effect (that is, a fine uneven surface). A reflective member 281 is disposed to face the first surface 271 of the light guide plate 270. In addition, the color liquid crystal display device 210 is disposed to face the second surface 273 of the light guide plate 270. Further, a diffusion sheet 282 and a prism sheet 283 are disposed between the color liquid crystal display device 210 and the second surface 273 of the light guide plate 270. Light emitted from the light source 260 is incident on the light guide plate 270 from the first side surface 274 of the light guide plate 270 (for example, the surface corresponding to the bottom surface of the truncated quadrangular pyramid), and collides with the uneven portion 272 of the first surface 271. Scattered from the first surface 271, reflected by the reflecting member 281, reentered the first surface 271, exited from the second surface 273, passed through the diffusion sheet 282 and the prism sheet 283, and The liquid crystal display device 210 is irradiated.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. The configuration and structure of the GaN-based semiconductor light-emitting device described in the embodiments, and an image display device, a planar light source device, and a color liquid crystal display device assembly in which such a GaN-based semiconductor light-emitting device is incorporated are examples. Constituent members, materials, and the like are also examples, and can be changed as appropriate. The order of stacking in the GaN-based semiconductor light emitting device may be reversed. A direct-view image display device may be an image display device that projects an image on a human retina.

  The description of the color reproduction range (chromaticity diagram) has been described exclusively using an image display device as an example, but the same color reproduction range can be expanded also in a planar light source device.

  Further, in the image display device, the planar light source device, and the liquid crystal display device assembly, three kinds of light emitting elements emit four or more colors, but N kinds (however, N ≧ 4). A light emitting element may emit (N + 1) or more colors.

  Further, an image display that emits light of (P + Q) color with a set of (P + Q) [where Q = 1, 2, 3,... It can also be a device, a planar light source device, or a liquid crystal display device assembly.

That is, for example, in the image display device according to the first or second aspect of the present invention, the planar light source device of the present invention, and the planar light source device in the liquid crystal display device assembly of the present invention, the embodiment As described in the above, it is preferable that one GaN-based semiconductor light-emitting device emits light of different wavelengths based on different operating current densities. By preparing as a set and driving each GaN-based semiconductor light-emitting element at a different operating current density, it is also possible to emit light of different wavelengths from each GaN-based semiconductor light-emitting element. That is, for example, two identical second light emitting elements made of green light emitting GaN-based semiconductor light emitting elements are grouped, and light of λ ₁ = 520 nm (green) is emitted from _one second light emitting element, and the other second light emitting element is emitted. A structure in which light of λ ₂ = 484 nm (blue green) is emitted from the two light emitting elements can also be employed.

Alternatively, in other words, the image display apparatus according to the first aspect of the present invention includes a first image display apparatus including a first light emitting element that emits blue light, and a second image display apparatus including a second light emitting element that emits green light. A second image display device, and a third image display device including a third light emitting element that emits red light. The first image display device, the second image display device, and the blue and green emitted from the third image display device And an image display device in which an image is formed by red light,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
A fourth image display device including a fourth light emitting element that emits a fourth color composed of the GaN-based semiconductor light emitting element;
At least one of the first light-emitting element, the second light-emitting element, and the third light-emitting element formed of the GaN-based semiconductor light-emitting element, and the fourth light-emitting element have different wavelengths based on different operating current densities. Is characterized by emitting light.

Alternatively, in other words, the image display apparatus according to the second aspect of the present invention includes a first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light. An image display device in which the configured light emitting element units for displaying a color image are arranged in a two-dimensional matrix,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The light emitting element unit further includes a fourth light emitting element that emits a fourth color composed of the GaN-based semiconductor light emitting element,
At least one of the first light-emitting element, the second light-emitting element, and the third light-emitting element formed of the GaN-based semiconductor light-emitting element, and the fourth light-emitting element have different wavelengths based on different operating current densities. Is characterized by emitting light.

Alternatively, in other words, the surface light source device of the present invention, or the surface light source device in the liquid crystal display device assembly of the present invention,
A planar light source device for irradiating a transmissive or transflective liquid crystal display device from the back,
A first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
A fourth light-emitting element that emits a fourth color composed of the GaN-based semiconductor light-emitting element;
At least one of the first light-emitting element, the second light-emitting element, and the third light-emitting element formed of the GaN-based semiconductor light-emitting element, and the fourth light-emitting element have different wavelengths based on different operating current densities. Is characterized by emitting light.

  The temperature characteristics (temperature-emission wavelength relationship) of the AlGaInP-based semiconductor light-emitting element or GaN-based semiconductor light-emitting element are obtained in advance, and the AlGaInP-based semiconductor light-emitting element or GaN-based semiconductor light emission in the planar light source device or color liquid crystal display device assembly is obtained. By monitoring the temperature of the element, it is possible to realize stable operation of the AlGaInP-based semiconductor light-emitting element and the GaN-based semiconductor light-emitting element immediately after the power is turned on.

  In addition, the drive circuit disclosed in Japanese Patent Application Laid-Open No. 2003-22052 can also be used as the drive circuit. The driving circuit includes a light emission wavelength correction unit that corrects a variation in light emission wavelength among a plurality of GaN-based semiconductor light-emitting elements by controlling a current supplied to the GaN-based semiconductor light-emitting element, and luminance between the GaN-based semiconductor light-emitting elements. It has a light emission luminance correction means for correcting the variation. Here, the emission wavelength correction means has a current mirror circuit provided for each driven GaN-based semiconductor light-emitting element, and the current mirror circuit can be configured to adjust the current flowing through the GaN-based semiconductor light-emitting element. . The current flowing through the reference side of the current mirror circuit is controlled by controlling the current flowing through the plurality of active elements connected in parallel. The light emission luminance correction means may have a constant current circuit that supplies current to the driven GaN-based semiconductor light emitting element, and may be configured to control on / off of the switching element of the constant current circuit.

FIG. 1 shows a concept of a projection-type color display image display apparatus (image display apparatus according to the first embodiment) including the first light-emitting element panel, the second light-emitting element panel, and the third light-emitting element panel in the first embodiment. FIG. FIG. 2A is a circuit diagram of a passive matrix type light emitting element panel in Example 1, and FIG. 2B is a schematic diagram of a light emitting element panel in which light emitting elements are arranged in a two-dimensional matrix. FIG. FIG. 3 is a circuit diagram of an active matrix type light emitting element panel according to the first embodiment. FIG. 4 shows a blue light emitting first light emitting element, a green light emitting GaN-based semiconductor light emitting element, a red light emitting AlGaInP semiconductor light emitting element (third light emitting element) in the image display device of Example 1. It is a figure which shows typically the pulse current which drives an element. FIG. 5 shows a blue light emitting first light emitting element (light emitting one color), a second light emitting element composed of a green light emitting GaN-based semiconductor light emitting element (light emitting one color), and a red color shown in FIG. 6 is a graph (chromaticity diagram) showing a color reproduction range when a light emitting AlGaInP-based semiconductor light emitting element (third light emitting element that emits one color) is driven. 6 shows a first light emitting element that emits blue light, a second light emitting element that is made of a GaN-based semiconductor light emitting element that emits green light, and an AlGaInP semiconductor light emitting element that emits red light (third light emitting element). It is a figure which shows typically the pulse current which drives an element. FIG. 7 shows a blue light emitting first light emitting element (light emitting one color), a second light emitting element composed of a green light emitting GaN-based semiconductor light emitting element (light emitting two colors), and a red current shown in FIG. It is a graph (chromaticity diagram) showing a color reproduction range when a light emitting AlGaInP-based semiconductor light emitting element (third light emitting element, which emits one color) is driven. FIG. 8 shows a blue light emitting first light emitting element (emitting two colors), a green light emitting GaN-based semiconductor light emitting element (two colors emitting), and It is a graph (chromaticity diagram) showing a color reproduction range when driving a red light emitting AlGaInP-based semiconductor light emitting element (third light emitting element, emitting one color). FIG. 9 shows a blue light emitting first light emitting element, a green light emitting GaN-based semiconductor light emitting element, a red light emitting AlGaInP semiconductor light emitting element (third light emitting element) in the image display device of Example 1. It is a figure which shows typically the pulse current which drives an element. FIG. 10 shows a blue light emitting first light emitting element (light emitting two colors), a second light emitting element composed of a green light emitting GaN-based semiconductor light emitting element (light emitting three colors), and a red color shown in FIG. It is a graph (chromaticity diagram) showing a color reproduction range when a light emitting AlGaInP-based semiconductor light emitting element (third light emitting element, which emits one color) is driven. FIG. 11 is a diagram conceptually showing a layer structure in the GaN-based semiconductor light-emitting element of Example 1. 12A is a schematic cross-sectional view of the GaN-based semiconductor light-emitting element of Example 1, and FIG. 12B is a drive current for driving the GaN-based semiconductor light-emitting element of Example 1. It is a figure which shows typically a pulse waveform. FIG. 13 is a conceptual diagram showing a state in which a drive current is supplied to the GaN-based semiconductor light-emitting element for evaluation of the GaN-based semiconductor light-emitting element. 14A is a schematic view of the GaN-based semiconductor light-emitting element as viewed from above, and FIG. 14B is a schematic cross-sectional view taken along arrow BB in FIG. (However, the hatched lines are omitted). FIG. 15 is a schematic view of two GaN-based semiconductor light-emitting elements connected in series as viewed from above. FIG. 16 is a graph showing the results of measuring the relationship between the operating current density and the light output of the GaN-based semiconductor light-emitting elements of Example 1 and Comparative Example 1. FIG. 17 is a graph showing the relationship between the operating current density and the emission peak wavelength of the GaN-based semiconductor light-emitting elements of Example 1 and Comparative Example 1. FIG. 18 is a conceptual diagram of a color display projection type image display apparatus (image display apparatus according to the mode 1B) of Example 3 having three sets of GaN-based semiconductor light-emitting elements and light passage control devices. FIG. 19 shows a modification of the color display projection type image display device according to the third embodiment (image display device according to the mode 1D) including three sets of GaN-based semiconductor light-emitting elements and a light passage control device. It is a conceptual diagram. FIG. 20 is a conceptual diagram of a color display projection-type image display device (image display device according to the 1C mode) of Example 4 having three sets of light emitting element panels and light passage control devices. FIG. 21 is a conceptual diagram of a modified example (image display apparatus according to the mode 1E) of a color display projection type image display apparatus according to Example 4 having three sets of light emitting element panels and a light passage control device. It is. FIG. 22 is a circuit diagram of an active matrix type direct-view color display image display apparatus (image display apparatus according to a second A embodiment) in the fifth embodiment. FIG. 23 is a conceptual diagram of a projection-type image display device (image display device according to modes 2A and 2B) of Example 5 including a light-emitting element panel in which GaN-based semiconductor light-emitting elements are arranged in a two-dimensional matrix. It is. FIG. 24A is a diagram schematically showing the arrangement and arrangement of light emitting elements in the planar light source device of Example 6, and FIG. 24B is a planar light source device and a color liquid crystal display device. It is a typical partial sectional view of an assembly. FIG. 25 is a schematic partial sectional view of a color liquid crystal display device. FIG. 26 is a conceptual diagram of a color liquid crystal display device assembly of Example 7. FIG. 27 is a graph plotting the emission peak wavelength against the drive current density of a GaN-based light emitting diode emitting blue light. FIG. 28 is a graph plotting the emission peak wavelength against the drive current density of a GaN-based light emitting diode that emits green light. FIG. 29 shows that λ ₁ = 520 nm (green), λ ₂ = when the emission wavelength of the GaN-based semiconductor light-emitting element constituting the second light-emitting element emitting green light is λ ₁ (nm) and λ ₂ (nm). It is a spectrum figure of 484 nm (blue green).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 ... GaN-type semiconductor light-emitting device, UN ... Light-emitting device unit, 10 ... Substrate, 11 ... Buffer layer, 12 ... Undoped GaN layer, 13 ... N-type conductivity First GaN-based compound semiconductor layer, 14 ... undoped GaN layer, 15 ... active layer, 16 ... undoped GaN layer, 17 ... second GaN-based compound semiconductor layer having p-type conductivity type 18 ... Mg-doped GaN layer, 19A ... n-type electrode, 19B ... p-type electrode, 21 ... submount, 22 ... plastic lens, 23A ... gold wire, 23B ..External electrode, 24... Reflector cup, 25 .. heat sink, 26... Drive circuit, 27... Controller, 28. ..Driver 41 43 ... Column driver, 42, 44 ... Row driver, 45 ... Driver, 50 ... Light emitting element panel, 51 ... Support, 52 ... X-direction wiring, 53 ... Y-direction wiring, 54 ... transparent substrate, 55 ... micro lens, 56 ... projection lens, 57 ... dichroic prism, 58 ... liquid crystal display device, 59 ... light guide member , 102 ... Heat sink, 200, 200A ... Color liquid crystal display assembly, 210 ... Color liquid crystal display, 220 ... Front panel, 221 ... First substrate, 222 ... Color filter, 223 ... overcoat layer, 224 ... transparent first electrode, 225 ... alignment film, 226 ... polarizing film, 227 ... liquid crystal material, 230 ... rear panel, 231 .... Second substrate, 232 ... Switching element, 234 ... Transparent second electrode, 235 ... Alignment film, 236 ... Polarizing film, 240 ... Planar light source device, 241 ... Housing, 242A ... Bottom of housing, 242B ... Side of housing, 243 ... Outer frame, 244 ... Inner frame, 245A, 245B ... Spacer, 246 ... Guide member, 247 ... Bracket member, 251 ... Diffuser plate, 252 ... Diffuser sheet, 253 ... Prism sheet, 254 ... Polarization conversion sheet, 255 ... Reflective sheet, 250 ... Planar light source 260, light source, 270, light guide plate, 271, first surface of light guide plate, 272, uneven portion on first surface, 273, second surface of light guide plate, 274 ..First side surface of light guide plate 275 ... Second side surface of light guide plate, 276 ... Third side surface of light guide plate, 281 ... Reflective member, 282 ... Diffusion sheet, 283 ... Prism sheet

Claims (23)

A first image display device including a first light emitting element that emits blue light, a second image display device including a second light emitting element that emits green light, and a third image including a third light emitting element that emits red light. An image display device comprising a display device, wherein an image is formed by blue, green and red light emitted from the first image display device, the second image display device and the third image display device,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities. A light-emitting element unit for displaying a color image, which is composed of a first light-emitting element that emits blue light, a second light-emitting element that emits green light, and a third light-emitting element that emits red light, is a two-dimensional matrix. An image display device comprising an array,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting element emits light having different wavelengths based on different operating current densities. The GaN-based semiconductor light-emitting element is
(A) a first GaN compound semiconductor layer having an n-type conductivity,
(B) an active layer having a multiple quantum well structure comprising a well layer and a barrier layer separating the well layer and the well layer; and
(C) a second GaN compound semiconductor layer having p-type conductivity,
With
D ₁ The well layer density of the 1GaN based compound semiconductor layer side in the active layer, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, the well in the active layer so as to satisfy d _1> d ₂ The image display device according to claim 1, wherein a layer is disposed. The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (2t _0/3) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound When the well layer density in the second active layer region from the semiconductor layer side interface to the thickness (t _0/3 ) is d ₂ , the well layers in the active layer are arranged so as to satisfy d ₁ > d _2. The image display device according to claim 3, wherein: The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (t _0/2) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound When the well layer density in the second active layer region from the semiconductor layer side interface to the thickness (t _0/2 ) is d ₂ , the well layers in the active layer are arranged so as to satisfy d ₁ > d _2. The image display device according to claim 3, wherein: The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (t _0/3) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound when the thickness of the semiconductor layer side interface (2t _0/3) the well layer density in the active layer within the second region up to and d _2, the well layer in the active layer is arranged so as to satisfy d _1> d ₂ The image display device according to claim 3, wherein: 4. The image display device according to claim 3, wherein a well layer in the active layer is disposed so as to satisfy d ₂ / d ₁ ≦ 0.8. (D) an underlayer containing In atoms formed between the first GaN-based compound semiconductor layer and the active layer, and
(E) a superlattice structure layer formed between the active layer and the second GaN-based compound semiconductor layer and containing a p-type dopant;
The image display device according to claim 3, further comprising: The second light emitting element that emits green light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light-emitting element is λ ₁ (nm) and λ ₂ (nm),
510 (nm) ≦ λ ₁ ≦ 540 (nm), and
470 (nm) ≦ λ ₂ ≦ 510 (nm)
The image display device according to claim 1, wherein the image display device satisfies the following. The second light emitting element that emits green light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light emitting device is λ ₁ (nm), λ ₂ (nm), and λ ₃ (nm),
510 (nm) ≦ λ ₁ ≦ 540 (nm),
490 (nm) ≦ λ ₂ ≦ 510 (nm), and
470 (nm) ≦ λ ₃ ≦ 490 (nm)
The image display device according to claim 1, wherein the image display device satisfies the following. The first light emitting element that emits blue light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light-emitting element is λ ₁ (nm) and λ ₂ (nm),
430 (nm) ≦ λ ₁ ≦ 460 (nm), and
455 (nm) ≦ λ ₂ ≦ 470 (nm)
The image display device according to claim 1, wherein the image display device satisfies the following.   The image display device according to claim 1, further comprising a light valve. A planar light source device for irradiating a transmissive or transflective liquid crystal display device from the back,
A first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light,
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light emitting device emits light of different wavelengths based on different operating current densities. The GaN-based semiconductor light-emitting element is
(A) a first GaN compound semiconductor layer having an n-type conductivity,
(B) an active layer having a multiple quantum well structure comprising a well layer and a barrier layer separating the well layer and the well layer; and
(C) a second GaN compound semiconductor layer having p-type conductivity,
With
D ₁ The well layer density of the 1GaN based compound semiconductor layer side in the active layer, when the well layer density of the 2GaN based compound semiconductor layer side was d _2, the well in the active layer so as to satisfy d _1> d ₂ The planar light source device according to claim 13, wherein a layer is disposed. The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (2t _0/3) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound When the well layer density in the second active layer region from the semiconductor layer side interface to the thickness (t _0/3 ) is d ₂ , the well layers in the active layer are arranged so as to satisfy d ₁ > d _2. The planar light source device according to claim 14, wherein: The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (t _0/2) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound When the well layer density in the second active layer region from the semiconductor layer side interface to the thickness (t _0/2 ) is d ₂ , the well layers in the active layer are arranged so as to satisfy d ₁ > d _2. The planar light source device according to claim 14, wherein: The total thickness of the active layer is t _0, the 1GaN compounds thickness from the semiconductor layer side interface of the active layer (t _0/3) d ₁ of the well layer density in the active layer and the first region to, the 2GaN compound when the thickness of the semiconductor layer side interface (2t _0/3) the well layer density in the active layer within the second region up to and d _2, the well layer in the active layer is arranged so as to satisfy d _1> d ₂ The planar light source device according to claim 14, wherein: The planar light source device according to claim 14, wherein the well layer in the active layer is disposed so as to satisfy d ₂ / d ₁ ≦ 0.8. (D) an underlayer containing In atoms formed between the first GaN-based compound semiconductor layer and the active layer, and
(E) a superlattice structure layer formed between the active layer and the second GaN-based compound semiconductor layer and containing a p-type dopant;
The planar light source device according to claim 14, further comprising: The second light emitting element that emits green light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light-emitting element is λ ₁ (nm) and λ ₂ (nm),
510 (nm) ≦ λ ₁ ≦ 540 (nm), and
470 (nm) ≦ λ ₂ ≦ 510 (nm)
The planar light source device according to claim 13, wherein: The second light emitting element that emits green light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light emitting device is λ ₁ (nm), λ ₂ (nm), and λ ₃ (nm),
510 (nm) ≦ λ ₁ ≦ 540 (nm),
490 (nm) ≦ λ ₂ ≦ 510 (nm), and
470 (nm) ≦ λ ₃ ≦ 490 (nm)
The planar light source device according to claim 13, wherein: The first light emitting element that emits blue light is composed of a GaN-based semiconductor light emitting element,
When the emission wavelength of the GaN-based semiconductor light-emitting element is λ ₁ (nm) and λ ₂ (nm),
430 (nm) ≦ λ ₁ ≦ 460 (nm), and
455 (nm) ≦ λ ₂ ≦ 470 (nm)
The planar light source device according to claim 13, wherein: A transmissive or transflective liquid crystal display device, and a liquid crystal display device assembly comprising a planar light source device for irradiating the liquid crystal display device from the back,
The planar light source device includes a first light emitting element that emits blue light, a second light emitting element that emits green light, and a third light emitting element that emits red light.
At least one light emitting element among the first light emitting element, the second light emitting element and the third light emitting element is composed of a GaN-based semiconductor light emitting element,
The GaN-based semiconductor light-emitting device emits light of different wavelengths based on different operating current densities.

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